refactor to introduce AGOAuth2Session and store refresh token
Refresh token request
Expiration test
Apply success callback method if access token still valid
Remove session storage of unused authorization code
Cleaning doc
More tests authz OAuth2 module
update cocoapods to latest to please Mr Travis
Update to OCMock 2.2.3 to fix OCMarg any
Fixing spelling
Merge branch 'AGIOS-145.refresh'