Close #18 - Basic API authentication is possible again

I've prevented the unhandled exceptions and converted them
into standard exceptions. This way, it seems that the basic auth
filter catches the exceptions and validates the api token.
Merge pull request #30 from beubi/master

Restores basic api authentication functionality
add support for READ Permission to the embeddable build status icon
Updated logic to a workable situation
updated help file
removed unused import
Fixed some issues with the baseURI being different, also this tests for an absolute match of the requestPath making it more secure.
Merge branch 'master' of git://github.com/4np/github-oauth-plugin