Fixed failing tests on JDK8

1. ParentIDFinderTest was failing because in JavaFX 8 you can't create Controls outside of the JavaFX application thread. To fix this an easy workaround is to create a JFXPanel in the setup method of the test.

2. ControllerLookupApplicationTest was ignored and not fixed because the underlying behaviour changed in JavaFX 8. It seems to be not possible anymore to overwrite the fx:id in an fx:include tag.
Fix for issue #12.

Due to the guice documentation (http://google.github.io/guice/api-docs/3.0/javadoc/com/google/inject/Binder.html) when the `toInstance` method is used guice is injecting all annotated fields of the instance when the Injector is created. For this reason the injection is performed twice. Using a provider is fixing this problem.
Merge pull request #14 from lestard/fix_issue_12_multiple_instances_created

Fix issue 12 multiple instances created