Adding a GAE sample app

u2f-gae-demo/.classpath

u2f-gae-demo/.project

...ae-demo/.settings/com.google.appengine.eclipse.core.prefs

u2f-gae-demo/.settings/com.google.gdt.eclipse.core.prefs

u2f-gae-demo/.settings/com.google.gwt.eclipse.core.prefs

u2f-gae-demo/.settings/org.eclipse.jdt.core.prefs

...o/.settings/org.eclipse.wst.common.project.facet.core.xml

u2f-gae-demo/src/META-INF/jdoconfig.xml

u2f-gae-demo/src/META-INF/persistence.xml

u2f-gae-demo/src/com/google/u2f/gaedemo/AppModule.java

...com/google/u2f/gaedemo/MyGuiceServletContextListener.java

u2f-gae-demo/src/com/google/u2f/gaedemo/MyServletModule.java

...e-demo/src/com/google/u2f/gaedemo/admin/AdminServlet.java

...c/com/google/u2f/gaedemo/impl/ChallengeGeneratorImpl.java

...e-demo/src/com/google/u2f/gaedemo/impl/DataStoreImpl.java

...c/com/google/u2f/gaedemo/servlets/BeginEnrollServlet.java

...src/com/google/u2f/gaedemo/servlets/BeginSignServlet.java

.../com/google/u2f/gaedemo/servlets/FinishEnrollServlet.java

...rc/com/google/u2f/gaedemo/servlets/FinishSignServlet.java

...src/com/google/u2f/gaedemo/servlets/GetTokensServlet.java