Rename AbstractEntity.postConstruct() to init()
Override AbstractApplication.init()

- AbstractApplication.init() logs warning that the method will be
  most likely be deprecated in a future release.
- Override init() in sub-classes.
KarafSshDriver: expandedInstallDir is protected

- Needs to be protected for sub-types that override install()
- TODO: Should this be protected (rather than private) in all
  our entity driver? Probably!
Merge pull request #632 from aledsage/fix/rename-postConstuct-to-init

rename postConstruct() to init()