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
Now I see that you've added a lot of different rules into this jar. I will add other libs into build.gradle.
If you added some extra rules into removed jar you'd better move them into separate jar/directory. Otherwise you need to migrate all custom rules manually every new pmd is released what is not comfortable to maintenance :(