l10n: extract and almost localize strings.
Add extra strings for near-future features.
More localization work.
Prepare v0.2
Removed extra param.
Removed more unused params.
[bug 1033476] Added option for updating cache.

This is only available if the documents cached are less than 5.
TODO: Cache topics too.
Added UI improvments for updating cache.

Also updated gulpfile with a new 'loading.gif' image.
Fixed document keys.
Code cleanup.
Correct key is now used to fetch a document.
Working "Cache all documents".
Optimizations for caching all docs.

Also removed some (now) dead code.