* develop: (21 commits)
  [td-225] fix bugs in multi-vnode projection query.
  support GCC 4.8
  [td-225]
  fix failed test cases
  [TD-161]
  [TD-161]
  [TD-161]
  avoid a potential bug
  tsdb notify the vnode about it status changes
  [td-225] refactor hash function
  [td-225] fix bugs for leastsquares query.
  [td-225] fix bugs at client
  [td-225] fix bugs for 256 columns data check
  use tbname in function tbid()
  single table subscribe is done
  super table subscribe is done
  build VgroupTableInfo
  fix typo
  add taosArrayClear
  enhance exception handling
  ...

support GCC 4.8

Feature/query

[TD-307]

Feature/subscribe

Develop lihui

tsdb notify the vnode about it status changes

Feature/query

* develop:
  scripts
  scripts
  fixup: typo.
  reduce test case to accelerate valgrind time.
  increase valgrind threshold to 12, definitely lost theshold to 13.

Hotfix/increase valgrind threshold to12

fixup: typo.

* develop:
  if link is new, server force the client to do authentication
  scripts
  [TD-275] fix drop table error while query from super table
  scripts
  fix column/metircs.sim
  [TD-292] client may crash if column too log
  [TD-292] scripts
  [TD-292] fix bug while columns too large
  restart TSDB when sync finished

if link is new, server force the client to do authentication