Optimizing imports
 * removing unused ones
 * eliminating wildcards
 * ensuring alphabetical order
fixing license mix issue - we're using Apache one
moving Version class to _private package
Eliminating REQUIRED flag because now when OPTIONAL flag is gone all dependencies are REQUIRED.
At ProblemReport.addProblem, update maxSeverityLevel if new severity is larger than current maxSeverity value
WIP (tests broken, do not pull): Revert transaction if report is not committable.
Also, invoke commit listener when transaction is rolling back (under review).