Implement correct enable/disable behavior for client side
Base for Vaadin RPC Offline
Initial version with offline support

Contains:
* Offline detection + online/offline events
* DataStore which either caches (local storage) updates or uses rpc to send them immediately
* DataStore which caches (local storage) all addresses
* OfflineRedirector which handles transitions between "/" and "/offline/"

Missing:
* Cache manifest
* Header in offline mode (vertical/horizontallayout can't be used on client side)
* Sensible offline UI (save button seemingly does nothing etc)
Ignore IDEA project files
Merge branch 'master' of https://github.com/Artur-/hybrid into Artur--master
Refactored merged files to follow the package naming in the rest of the
project

Conflicts:
	src/main/java/org/vaadin/hybrid/ClientWidgetSet.gwt.xml
	src/main/java/org/vaadin/hybrid/HybridUI.java