Renaming Loggable -> HierarchialLoggable

Doing this in order to avoid confussion with a proper logging system
like log4j/logback
Renaming HierarchialLogger packages

...so that it is consisten with arena packages
Merge pull request #11 from uqbar-project/hierarchial-logger-rename

Hierarchial logger rename
Forcing Java-8 Compatible Javassist version
Removing old javassit with different groupid