Added support for notifications customisable per request and managed in the worker thread
Merge branch 'enhanced-notifications' into master-fixed

Conflicts:
	robospice-core-parent/robospice/src/main/java/com/octo/android/robospice/notification/NotificationRequestProcessor.java
	robospice-core-parent/robospice/src/main/java/com/octo/android/robospice/request/RequestProcessor.java