Prevent multiple uses of an auth code

Fix #36 by changing the expiration date of the auth code.
Note that it changes the interface and requires to bump version number.
Merge branch 'Spomky-AuthCode-expiration'
Merge branch 'Spomky-AuthCode-expiration'
Files moved and namespaces modified
Implicit Grant Stub prepared
Implicit Grant removed
Sync with upstream
Sync missing function
Grant & Exceptions
Bug fixed
Bug fixed
Bug fixed
Another missed bug
OAuth2Client abstract class moved