Remove SOURCE keyword by parsing as an identifier and checking the value

Reverts "IMPALA-1033: Remove SOURCE keyword; very common identifier"

Change-Id: I3fcf6d02786e00287b564cff0a823d0c19504e7a
Reviewed-on: http://gerrit.ent.cloudera.com:8080/3341
Reviewed-by: Matthew Jacobs <mj@cloudera.com>
Tested-by: jenkins
Fixed UDF memory leak warning for STDDEV

Change-Id: I8df3d28e9dc0f06819f6512c175b5dec4210a329
Reviewed-on: http://gerrit.ent.cloudera.com:8080/3312
Reviewed-by: Victor Bittorf <victor.bittorf@cloudera.com>
Tested-by: jenkins
CDH-19918: fixed Moscow timezone conversion.

Conversion from UTC to Moscow time was incorrect, this has been fixed.

Change-Id: Ib2a1720424bffff4f09713bfb06b5046fb38c031
Reviewed-on: http://gerrit.ent.cloudera.com:8080/3311
Reviewed-by: Victor Bittorf <victor.bittorf@cloudera.com>
Tested-by: jenkins
Add CASE decimal builtin.

Change-Id: I007e7f319acd6a5bce739a08797d1d87ffc64472
Reviewed-on: http://gerrit.ent.cloudera.com:8080/3275
Reviewed-by: Nong Li <nong@cloudera.com>
Tested-by: jenkins
FE changes to avoid shipping null-type expressions to the BE.

Once the expr refactoring goes in, the BE will not be able to evaluate
any TYPE_NULL exprs. This patch ensures that the FE casts all null
literals and slot refs before they reach the BE.

There are a bunch of places where we know the appropriate type and
just weren't using it before. This patch also introduces a few notable
hacks:

* Serializing null SlotRefs and NullLiterals as boolean NullLiterals
  in case they weren't cast earlier.
* Converting null SlotRefs to NullLiterals in uncheckedCastTo() since
  we don't need to read from the slot at all.

This works, but we should consider adding a final pass that cleans up
the plan tree and takes care of this.

Change-Id: Ic2ee181139059553d7f2d0e17e9dacaee241df17
Reviewed-on: http://gerrit.ent.cloudera.com:8080/3294
Reviewed-by: Skye Wanderman-Milne <skye@cloudera.com>
Tested-by: jenkins