Fixing google docs key regex

Some google docs have an underscore and/or a dash in the key. [See this doc for an example.](https://docs.google.com/spreadsheet/ccc?key=0AoCe6lq_0U-_dEhQTHlRT0VDTGtVZWhIa21iQUdDVnc&usp=sharing) This patch supports those docs.