chore(bower): add .bower.json (already registred)

I created a .bower.json and registred it using
```
bower register webL10n git@github.com:edouard-lopez/webL10n.git
```
So now you can simply install it using:
```
bower install webL10n
```
More info on registering package at https://github.com/bower/bower#registering-packages