Remove trailing whitespace from all .java files.
Organizing imports in all .java files.
Adding missing @Overrides.
Add save actions to enforce these (at least in Eclipse).

Enforces:
- No extra whitespace at end of line
- Organized imports
- @Override annotations wherever appropriate

Does not yet enforce/choose a side on spaces vs. tabs for indentation.

Consistency here should make it easier to CR changes from people whose
editors already do these things.
Merge pull request #36 from ggp-org/whitespace

Whitespace and other consistency changes