Add setBasicAuth
Bump version to 0.3.1
Merge branch 'add_basic_auth' of git://github.com/lukerandall/http-streams into basic-auth
Rename function to setAuthorizationBasic

Rename setBasicAuth function to setAuthorizationBasic to facilitate a
later parallel function setAuthorizationDigest or so.

Add test case using example from Wikipedia.
Add documentation for setAuthorizationBasic