i18n: big refactor

Each translatable string have to be marked with the css class "i18n"
Add a new ?i18nextract URL parameter that extract all string that can be translated/corrected
Separate each translation in a file, add a grunt task to recombine them
Try to auto-detect user language and translate web.

Conflicts:
	bitaddress.org.html
	src/ninja.onload.js
Merge branch 'master' into i18n
mark most of the string as translatable (except FAQ, release note)
clean dead code
remove the useless vanity wallet
translatable title
fix the last quirks for i18n
Add "Who are you ?" and "How can I help ?" questions in the FAQ
add French translation
Merge branch 'dev'