Add spilling test for an analytic fn

Change-Id: Ia93c71c9c2a01f7f04a81593d51f5ca565286b7d
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4447
Reviewed-by: Nong Li <nong@cloudera.com>
Tested-by: jenkins
Analysis error for min()/max() w/ analytic windows without UNBOUNDED PRECEDING

min()/max() do not currently support windows without UNBOUNDED PRECEDING,
so this changes AnalyticExpr to detect this during analysis and throw an
AnalysisException.

Also removed some stale TODOs in the BE

Change-Id: I734b0a5d5399f9bb9d4db6ab1ddc079237b0ac03
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4431
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: jenkins
Move analytic fns test case for decimal to decimal.test

Change-Id: Ic6e02484f47f9a9c47924850c8cf12daf8574c8c
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4449
Reviewed-by: Ippokratis Pandis <ipandis@cloudera.com>
Tested-by: jenkins