upgraded Findbugs, Checkstyle and PMD

- removed pmd library: now it is loaded from maven repo
- added pmd-java library into build.gradle so java rules are taken from repo not local custom jar
- upgraded Findbugs, Checkstyle and PMD, resolved problem with dependencies
- minor changes required by new PMD API
- better support in case when findbugs throws exception when there is no file for analyzing
That would be nice if you pass such errors and results to show them in Gerrit results as a comment. In that case you can add something like this:
 Checkstyle: 0 volation(s)
 PMD: Could not find configuration file ...
 Checkstyle: 2 volation(s)

Instead of current solution that tells you only the final number without errors.