Update vimeo.php

I added the extra expl, to VimeoAPIException, the standard message is to vauge to know what is the real issue unless digging into the code.
Ex:
With just the VimeAPIExpection -> results are  
Fatal error: Uncaught exception 'VimeoAPIException' with message 'Invalid / expired token 
VimeoAPIException: Invalid / expired token in

--the two messages are the same with no real explanation

If you add the new Exception(expl), the results are:
Fatal error: Uncaught exception 'Exception' with message 'The oauth_timestamp passed is either too far in the past or in the future.
VimeoAPIException: Invalid / expired token 

--this new message at least narrows the issue with the server internal clock being incorrect.