QGen: Allow the reference db to return decimals instead of doubles
QGen: Allow the reference db to return decimals instead of doubles

Postgresql seems to return a decimal data type for some aggregate
functions whereas Impala returns a Double. This change allows the
reference db to return a Decimal. If Impala returns a Decimal, the
reference must still return a Decimal.

Change-Id: Ifd13d208e71e8f1a5b62ef66966daddb57cdd1ce
Reviewed-on: http://gerrit.cloudera.org:8080/336
Reviewed-by: Taras Bobrovytsky <72e4a6fc4c5ef23f318dc209e8402725249a5676@cloudera.com>
Tested-by: Casey Ching <77bc9a9984e6786c5799d7a71768cf023120ef76@cloudera.com>

cloudera/recordservice,cloudera/recordservice,cloudera/recordservice,cloudera/recordservice,cloudera/recordservice,cloudera/recordservice,cloudera/recordservice