merge request for complimentary purchase evaluator, need reviewers

[Alexey Grachev]

Hello,

if someone is interested on implementation of evaluation form 
complimentary purchase evaluator,

please, review, comment or contribute.

Here is the mr:

https://github.com/PredictionIO/template-scala-parallel-complementarypurchase/pull/7/files

Each review comment and each commit of Yours will be highly appreciated.

Thank you.

Alexey

ps. For the moment the problem is I dont know how to define the success 
of comparison between predicted and actual  bought items. I put comments 
on respective places in code.