Tests: Added the beginnings of a test using gwt-test-utils.

Tests: Added the beginnings of a test using gwt-test-utils.

* pom.xml: Add dependencies on gwt-test-utils and easymock.
* src/test/resources/META-INF/gwt-test-utils.properties: Add this file
which tells gwt-test-utils what class will be tested.
* src/test/java/org/glom/web/client/GwtTestOnlineGlom.java:
Add a simple (but empty) test case. One class, used by the OnlineGlom
class, is mocked so that it can be created. However, I am not sure
why only this class needs to be mocked.

Note that mockito seems more popular, and clearer, than easymock,
but I have not got that working yet. It might be a matter of the
mockito version.