TEIIDDES-1888: Replaces resource.getRawLocation with central utility method

* Possible for resources, especially projects, that are located in the
  default workspace location to lack a value for raw location. Even
  though they have a location the raw location returns null

* Replaces calls to getRawLocation with a getLocation function in ModelUtil
  that first tries getRawLocation then getLocation. If both are null then
  a core exception will be thrown
Fixes jboss tools usage dialog appearing in tests

* Disables the jboss tools usage request dialog appearing when running
  tests. This dialog can interfere with the few UI tests when executing
  in the IDE.

* Startup class changes the preference property to globally turn off the
  usage request.
Fixes incorrect string constant key