Merge pull request #38 from laurentvdl/PackageCacheVersionDetection

Package cache and version detection.
Possible solution for #39.
Further fix for #39.
Adds support for the 'Parent-Application-Context' bundle header for opting out of integrating the extension application context with the Alfresco application context.
Make BundleVersionDetector disposable as a prototype (kept large cache Map)
Use Sets to collect SystemPackages: avoid thousands of List.contains calls.
Merge pull request #40 from laurentvdl/master

Bundle version cache and Set<SystemPackage>
Minor refactorings to Java package scanning.
Package configuration moved to OSGI child application context.
Disabled AMP integration test.
Added Configuration page with explanation on system packages.
Added function to delete the System Package cache.
System Packages are now listed on a separate page.
Show notification when the Framework cannot be restarted.