Add responseType code and password with token refresh interval

[babelouest]

I've made some changes to implement code response type with a refresh_token.

If a refresh_token is present, then an interval is launched to get a new access_token before expiration.

Shouldn't be too long to implement oauth2 response_type password with that base.

[babelouest]

@andreareginato , @m00s , if you're interested, I've completed my pull request to add code and password response_type handling.

I added the following options to the directive:

• tokenPath to specify the token path (similar to authorizePath), required only for response types code and password
• disableCheckSession, default false, to disable the token check at startup. It's not necessary if the token contains its check using a signature for example

I also added a simple login form in the view.html for password response_type.

Then, the main modifications are in the file access_token with the support of the new response_type and the token refresh in an interval.

Concerning the password response_type, if the user checks the "Keep connection" checkbox, the directive will try to reconnect if the refresh_token becomes expired.

Some feedback would be appreciated :)