GWTII-164: Moved FeatureInfo sample to correct module.

Also removed dependency on VectorServerLayer and improved attribute builders.
GWTII-164: Added getLabel method to api.
GWTII-164: Checkstyle (tabs instead of spaces).
GWTII-164: Fixed @since annotation for getLabel.
GWTII-164: Removed unused messages.
GWTII-164: Decoupled options (actions) from FeatureInfo widget.
GWTII-164: Checkstyle and javadoc for FeatureActions.