rhbz978666 - add database table and liquibase change log for review translation comment
rhbz978666 - update TransUnit to indicate comment existance
rhbz978666 - UI and tests

- add review comment rpc
- get review comments rpc
- review comment gwt MVP
- change to TransUnit
- change to editor buttons display
- annotate a few areas that have technical debt (hibernate performance related)
Tech Debt: eager load text flow targets when we intended to access them
rename methods after refactor
revert optimization change

this is too big a refactoring and should do in its own pull request
rhbz978666 - add comment indicator
rhbz978666 - add comment indicator
minor clean up
rhbz978666 - comment change is broadcasted thru event service