Modifed .gitignore for java repo.
Moved a 'uno-repo' directory out of a 'resource' directory so that the target can be packaged without dependency by default.

* Moved jodconverter-core/src/main/resource/uno-repo to jodconverter-core/extra/
Removing dependencies on JDK 1.7+

* Removed uses of java.lang.Objects class.