Authorization way

Hi !

I look for an implementation in Bash of the Freebox API for a few weeks !
Thanks a lot for your code. For me, it looks very clean ; I like it :+1: 

During the coding of authorization phase, I met a problem while getting track_id :
```bash
$ echo '{"success":true,"result":{"app_token":"k8E5uJnMhZczl74IJzK3TTawytQuJg\/dcqk0WhYOhs8+x7PVKXldnl87wWtUp7RI","track_id":5}}' | sed -n -r 's/\\\//\//g;s/^ *\{//;s/\} *$//;s/.*"track_id":(.*)/\1/p'
5}
```
I didn't find any way to suppress the brace with sed... :(
So, I added a simple
```bash
tr -d '}'
```
This is the first commit.

The second one is a way to authorize a new application on the Freebox, and then to obtain a app_token.

I coded some other stuff in order to do all of that automatically (if login is wrong, then authorize, and login again), but it doesn't seem very usefull...