Update form_prototype.md

Only changed one word as I felt it was probably not the right word for the context. Hopefully once I actually work out how to do this I can suggest a better tutorial...
Improve Geolocation documentation

Improve documentation and update the default options list to the real
one.
Update index.md

Added a tip about recaptcha in entity form. As this is a common usage it might help people and avoid issues post.
Fix bug when intl extension is not installed

If a server has not the php intl extension, symfony use symfony/intl as
a replacement layer, it works only for english language and do not
implement all intl's features.
In this case, DateType call `\Locale::getPrimaryLanguage()` and throw an
Exception. This commit prevent this Exception.
Using translation keys in recaptcha validator
Merge pull request #347 from wysow/fix/recaptcha-translations

Using translation keys in recaptcha validator
Merge pull request #346 from WedgeSama/intl-fix

Fix bug when intl extension is not installed
Merge pull request #345 from Molkobain/patch-1

Update index.md
Merge pull request #344 from WedgeSama/master

Improve Geolocation documentation
Merge pull request #332 from doughayward0/patch-1

Update form_prototype.md
slovenian translation