Fix issue#1310, add two files pkg/config/system_vars.go pkg/config/system_vars_test.go to gitignore (#1316)

Signed-off-by: jinhai <haijin.chn@gmail.com>

Signed-off-by: jinhai <haijin.chn@gmail.com>

* Add IOPackage module. buffering and byte order need to be tuned;

* Add mysql client protocol.

* Make mysql client protocol works

* Add configuration related operation interface

* The configuration works

* Add ast transformer

* Add expression and selectstmt transformer

* Remove useless directories(types,session,sessionctx,util); change Subquery,TableExpr; add CaseExpr; add IntervalExpr; add IsTruthExpr; add DefaultVal; add Union Clause; add Insert Statement; “

* Fix decimal; add CreateTable

* Add origString for NumVal

* Fix decimal null value

* Rm some useless code

* Try to connect the frontend with the computation engine with the fake storage engine and the fake nodes

* The frontend are connected with the computation engine

* Fix parallel pipeline problem;
add DropTable, CreateDatabase, DropDatabase, Insert, Delete, Update,
LoadData, Begin, Commit , Rollback, Set(partial), Show(partial), Explain(partial), Use...

Signed-off-by: jinhai <haijin.chn@gmail.com>

Signed-off-by: jinhai <haijin.chn@gmail.com>