Improved translations

When using Codiad in french I noticed that some strings were not translated. I investigated and found two issues :
* Lots of keys in the translations don't match the format expected by the i18n function (first letter of each word in upper case).
* The javascript i18n function doesn't accept parameters/placeholders in string, which made strings like "Project {%Project Name%} Loaded" impossible to translate.

I tried to fix both issues, and as far as I can tell it's working fine.

Could you review this ?

Thanks !