Enhancement: Persistence details

Vitaly,

I found your development branch and it is very advanced to what Anton currently has.  I have made an few changes around the persistence model and would like you to consider merging it to your branch (vitalidze/dev).  I am more familiar with designing the database model and implementing the code around the model (coding before ORM) so please review my suggestions below for correctness.

I rebased my work off of your most recent commit.  I have provided six commits in this pull request to show the relevant incremental changes.  Most notable changes were updating all the plugin versions and removing specific references to Hibernate within the code.

- jss