* modify build dep

* Add missing packages

* clean installed third-party

* Modify docs

* update docs

* rebase upstream

* Add find path sentence.

* Add getFrontiers.

* Add findPath.

* Update visited vertex.

* Consider even length path.

* Add test no filter.

* Refactoring. Add tuple<id, +/-type, ranking> to indicate a step in a path.

* Support find all path.

* Refactoring the prepare part.

* Add shortest path test case.

* Enhancement with clearing the interim path.

* Verify result with string.

* Enhancement, and print edge in cmdprocessor.

* Add column type of path.

* Building path with ptr(Enhancement).

* Rebase and support multi edges

* Add multi edges test.

* 1. Use high priority for get-neighbors task when find path.
2. Update the formats in console for path.

* Debug: duplicate path found. Solution: clear ids before copy.

* Rebase and solve conflict.

* Remove barrier.

* Rebase and address comment.

* Support comparison function in().

* Update.

According to my practice, I think the  [manual](docs/README.md) is more about "How to use" than "How to get"， it's better divided in a new category.

2 Replace static_cast with dynamic_cast.

1. Add basic metrics for data operation in storage service
2. Add a storage integrity test tool in storage-perf.

close #287

Now we support following metrics: get_bound, bound_stats, vertex_props, edge_props, add_vertex, add_edge, del_vertex, update_vertex, update_edge.

We can get qps or latency from these metrics (add suffix), for example: vertex_props_qps or vertex_props_latency.

You can get a single metrics like this:
curl -G "http://127.0.0.1:50005/get_stats?stats=vertex_props_qps.rate.60

If you want get multiple metrics like this:
curl -G "http://127.0.0.1:50005/get_stats?stats=vertex_props_qps.rate.60,vertex_props_latency.avg.60,vertex_props_latency.p99.60&returnjson"
We can get qps, avg latency and p99 latency in a minutue.

You can get all metrics like this:
curl -G "http://127.0.0.1:50005/get_stats?stats"

The storage integrity tool is used for verifying data integrity in storage. It only works for single replica for now. You can use it like this:
./storage_integrity --meta_server_addrs=192.168.8.5:60001 --first_vertex_id=100 --width=1000 --height=1000

meta_server_addrs is the meta server addresss.
first_vertex_id is the first vertex id which we inserts.
width and height is the width and height of the big matrix.

* docs for RC1

* add limit

* add string operations

* fix minor

* update readme, and remove index.md

* add changelog.md

* move introductions to overview directory
fix space

* rebase master since Sep16

* fix bilibili address

* address laura's comment

* Fix fail to delete the vertex without edges

* add UT

1 When multiple statements contain empty statements.
2 When the function is called, if the first parameter of the parameter list is empty.

for example:
  ";MATCH"
  "floor( ,1)"

* modify verify kv

* invalidate leader when E_PART_NOT_FOUND returned

* fix balance data failed from one replica
build simple_kv_verify as a independent package

* enhance balancer

* Fix failed balancer_test

Add more ignored files for docker and exec clang-format before commit

* show space name in leader/part distribution of show hosts

* update

* fix space lock

* update

* address yixinglu's comments

* fix @wadeliuyi's comments and update docs

* fix crash when balance leader timeout

* support general storage in StorageService

* fix nebula benchmark crash

* Simple KV Verify Tool

* support uuid

* support uuid

* increase storage client

* Implement member change

* Address wadeliuyi's comments

* Add Balance UT

* Fix failed Meta http Uts

* Add balance data and balance data id command in console

* Fix bugs

* Fix stale peers when add part

* Fix bugs

* Remove retry logic and fix stale log response

* Address cirtical27's comments

* Fix snapshot_test

* Fix bug in snapshot

* Remove check in commitTransferLeader

* support nebula key type

* modify key structure

* update commit key

* use kSystem

* Fix giving wrong column names when union has only right result.

* Move index out explicitly.

* Add tests.

* Address @wadeliuyi's comment.

* Rebase and fix conflict.

* Address comment.

* Improved build concurrency

* Depend on parser

* Addressed @yixinglu's comment

* Fixed issue when ASAN enabled

Now, we support updating one vertex or edge with constraints， all operations about read-modify-write are atomic.

The filters and yields expressions in update sentence will be pushed down into storage layer.