Add translatable strings from OnlineGlom

* glom/onlineglom_strings.cc:
* Makefile.am:
* po/POTFILES.in: Mention the new file.
These strings are actually used here:
http://gitorious.org/online-glom/gwt-glom/trees/master/src/main/resources/org/glom/web/client/ui
and I must manually copy the translations across until I find a better way.