Very light grammar fix to improve gender-neutral

* Update devise.fr.yml

Consistencies across the French translation

* Update doorkeeper.fr.yml

* Make Reporting admin section translatable

And translate it into english and french

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

* Make subject of emails translatable and improve french translation

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

* Make error pages translatable and translate them in english and french

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

* Translate site setting section

* Insert instance in registration emails and improve them a bit

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

* Update devise.fr.yml fixing minor typos

* add missing strings

* Fix a translation and add translation for devise part

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

* French typo

* Datetime french translation

From https://gist.github.com/qsypoq/4cf3b858ff8242ffb013

Fix #68