add query/queryJoin.py to regression.

[TD-814] close fd on error occurs

metadata query test

Feature/stress tool

fix compile error on MEM_CHECK=true

Merge pull request #2538 from taosdata/hotfix/sangshuduo/fix-importDataLastSub-conn-lost-on-valgrind

fix importDataLastSub.py failed with valgrind.

[TD-827]

[TD-826]

fixbug use_after_free

fix create vnode multiple times problem

add general/parser/where.sim to regression test.

Feature/2.0tsdb

change http code

Feature/query

rand() is changed to random()