Fixed ERRAI-473: JPA2 method-accessed attributes don't work
Fixed ERRAI-474: Allow the addition of primitive attributes to entities that have been persisted

Pulled out LocalStorage into its own class so it could be used by the tests as well. Might come in handy later
on for other people too.
Merge branch 'master' into 3.0

Conflicts:
	errai-jpa/errai-jpa-client/src/test/java/org/jboss/errai/jpa/test/client/ErraiJpaTest.java
Better error message when PageNode impl returns null instead of a widget
Fleshed out the store list page and created a store editing page.

Notably, this commit adds Google Maps v3 integration to the app (for setting the store's location)