Author tests for all

Hi,

I fixed up the author tests so they will run with any given Github username and password.  This makes it easier for others to work on Net::GitHub.  I also replaced the dumps with actual tests.  I didn't look too close to see what the tests modify about the account, but I have a separate test account.  This isn't 100%, but it's way more usable than it was before.

* I couldn't get the oauth credential creation test to work.
* I couldn't get the blob test to work, it appears to be a problem on Github's side.

Most of the tests are read-only and probably don't need credentials.

For the future, I would suggest making a separate Github account just for the tests to use and hard code the API token.  This is what Gitpan does.