Issue38 - break proprietary ping into proper component

* removed gcm cruft from app
* added "default" for LoadExtensibleSection to allow for less app preconfig

@bbangert I think I grok what you've done. r?
When using the '.' in section names, TOML will consider it a nested structure, but it appears as a single one. So the above that I made is actually a hash of hashes, keyed by the second name. It'd be loaded as a single entry, so wouldn't affect LoadApplicationFromFileName(). We can go with a single option for now and revisit this later.