Provide a sensible category (same as bugzilla) for display in plugin category 

Suggestion from ent38 on http://plugins.netbeans.org/plugin/45919/mantisintegration
Optimize depedency specification:
- Centralize dependency versions (release and implementation versions) into properties
- Order dependencies
Add stub implementation of property change support in MantisRepository
=> make module compatible with 7.3-BETA2
Prepare for the 7.3-beta2 release
Remove @Override annotations on methods in MantisRepositoryProvider add only in the 7.3 cylce
=> prevent compile time error when build against 7.2
[maven-release-plugin] prepare release MantisIntegration-0.3