This adds "English (UK)" to the locale list, which allows for "tag
colours" and allows dates to be recognized in d/m/y form.
I changed "color" and "license" on Transifex, but I'll leave other words
for others to change. If we stick to Oxford spelling, there probably
won't be too much else.
The Firefox French language pack contains some mistakes regarding
the short form of months. As a consequence, French month parsing
didn't work.
Please note that these values aren't even the correct abbreviations
but only the three or four first letters of the correct abbreviations.
See the French CSL locale for the correct abbreviations.
Month values from the Firefox language packs are included in a
JSON file used by `Zotero.Date.getMonths()`. `getMonths(true)` includes
English months as well.
The JSON file should be bundled with the connectors as well, and
Zotero.Date.init() should be updated to populate the month data from
that.
