Post-jbmc move cleanup

[tautschnig]

• Introduce a goto-java (or the likes) to match goto-cc and get rid of janalyzer and jdiff (cf. remove usage of Java bytecode frontend #2118).
• CODEOWNERS are not up-to-date. -> Update CODEOWNERS #2216
• .gitignore is not up-to-date. -> Update CODEOWNERS #2216
• Cleanup the Travis configuration to run jbmc tests in parallel to cbmc ones - requires input on Increase parallelism in Travis builds #2047.