Bugfix: MLP predict using 1.12 model fails on later versions
Bugfix: MLP predict using 1.12 model fails on later versions

JIRA: MADLIB-1207

MADlib 1.12 did not support grouping in MLP. The summary table created
used to have the mean and std used for standardizing the independent
variable. From MADlib 1.13 onwards, grouping was supported, and the mean
and std were moved to the standardization table.
This resulted in a failure when MADlib 1.12 MLP models were used to
predict using MADlib 1.13. This commit fixes this issue.

Closes #237

njayaram2/madlib,hpandeycodeit/incubator-madlib,iyerr3/incubator-madlib,hpandeycodeit/incubator-madlib,njayaram2/madlib,orhankislal/incubator-madlib,iyerr3/incubator-madlib,orhankislal/incubator-madlib,orhankislal/madlib,madlib/madlib,hpandeycodeit/incubator-madlib,orhankislal/incubator-madlib,hpandeycodeit/incubator-madlib,madlib/madlib,orhankislal/incubator-madlib,njayaram2/incubator-madlib,hpandeycodeit/incubator-madlib,njayaram2/madlib,njayaram2/incubator-madlib,njayaram2/incubator-madlib,orhankislal/madlib,apache/incubator-madlib,apache/incubator-madlib,madlib/madlib,apache/incubator-madlib,orhankislal/madlib,njayaram2/madlib,madlib/madlib,orhankislal/madlib,orhankislal/madlib,iyerr3/incubator-madlib,iyerr3/incubator-madlib,iyerr3/incubator-madlib,orhankislal/incubator-madlib,njayaram2/incubator-madlib,njayaram2/incubator-madlib,apache/incubator-madlib,madlib/madlib,apache/incubator-madlib,njayaram2/madlib