Issue #27131 : Change les termes dans le backlogs plugin

platform: 2.3.1 supported: 2.2.4, 2.3.1 # supported: 2.2.4, 2.3.1
backlogs: 1.0.3 supported: 1.0.3 # supported: 1.0.3
ruby: 1.9.3 supported: 1.9.3, 2.0.0 # supported: 1.9.3, 2.0.0

I'm in a French Canadian office and these were the suggestions to improve the translation of the following terms:
* Story -> Scénarion
* Sprint -> Itération
* Backlog -> Carnet

It's not complete and not perfect, so it might get further modifications in the future.