* Use active hosts when creating space

* x

* support describe space

* support describe space

* support desc space

* address dangleptr's comment

* address dutor's comment

* using async

* address dangleptr's comment

* fix

* fix copyright

* address dangleptr's comment

* fix

* fix

* modify remove to drop in admin commands

* recovery remove hosts

* address laura-ding's comment

* Use ephemeral port to bind on in tests

* let the system choose an available port

* rebase master

* address dutor's comments

* Adjust meta client ctor  && implement heartbeat logic inside.

* Address laura-ding's comments

* Fix conflicts

* To add a web interface to indicate the status of the three daemons

* address dutor's comments

* address sherman-the-tank's comments

* address dutor's comments

* rebase master

* Support unreserved keywords

* Reserve keyword TAG, VERTEX and EDGE

* alter edge

* address comments

* address comments and fix error using typeId function

* Reorganized all linters into the same directory

* Fix

* support semicolon in console command

* using while to determine the loop ending

* All files committed in docs

* Update README.md

*  update nQGL

* fix typos in FindGPERF.cmake

*  fix typo in FindReadline.cmake

* fix table

*  fix table

* update readme 5.14.2019

* readme add slack link

* Remove space keyword in UseSpaceSentence && update get-started.md

* Update nGQL.md

* support show tags and edges

* support remove tag and edge

* address dangleptr's comments

* support edge in meta service

* support leader

* fix toString function defect

* address dangleptr's comments

* address dutor's comments

* Support IP:Port semantically

* Address @dangleptr's comments

* Fixed stupid compiling error

* add AlterEdgeProcessor, GetEdgeProcessor, RemoveEdgeProcessor

* address dangleptr's comment

* rebase master
modify SET to CHANGE

* fix UT

* Refactor the insertion syntax

* Fixed missing overwritable in vertex insertion

* Support some user sentences in Query Engine

* Support some user sentences in Query Engine

* Address comments

* Address comments

* 1.Improved logic of MissingOkClause. 2.Address comments

* Improve qualify member functions should return const value

* Address comments.

* Iplement alter tag executor and meta client

* Address comments.

* SchemaManager and StorageClient share one MetaClient instance

* address dangleptr's comment

* address dangleptr's comment

* address dangleptr's comment

* fix print

* 1. Rename Define schema to Create schema
2. Implements the processing of creating and retrieving schemas from graphd to metad

* Perfect unit testing
address steppenwolfyuetong's comment

* address dangleptr's comment

* Perfect unit testing

* fix nebula_native_client build failed

* fix nebula_native_client build failed

* fix nebula_native_client build failed

* address sherman-the-tank's comment

* address dangleptr's comment
address steppenwolfyuetong's comment

* Rename addTag to createTag
rebase master

* Uniform schema version

* fix alignment

* Added YieldExecutor

* Fixed typo

* Address @steppenwolfyuetong's comments

* Rebase and address @sherman-the-tank's comments

* Fixed stupid bugs

* Implement tag alter for serverBasedSchemaManager

* Added new status MetaNotExisted

* rebased

* Changed version from millisecond to Microsecond. And unified int64.MAX

* Fixed testcase. make sure get latest TagItem from unordered vector

* Changed alterTag logic

* Address comments.