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
Looked like problem with library https://github.com/TouK/sputnik/commit/046a091a91ebed7f658c7686cf84f6d91ee4ee31#diff-f6fe1516b6bc71d549f95fc28be965de so I restored it. Both passes so will remove it.