Changes done for GEB-310 - Support navigating to page instances in addition to classes.
- Extracted Interfaces for all the support classes.
- Added Uninitialized support implementations for the said interfaces
- Added PageInstanceNotInitializedException class.
Made changes according to review comments on pull request #85
Removing the methodMissing method that is already defined in the parent class
Merge branch 'geb-310' of https://github.com/menonvarun/geb
Fix a link from manual to javadoc after a signature change
Fix codenarc violations
Pull request polishing, adding some more test coverage
Document the fact that now page instances can also be passed to Browser methods that previously only accepted classes.