New feature: Ability to completely configure services with a single url

Previously services had to be configured by individually specifying
the host, post, ssl, etc.  Now you can specify an absolute url to
the service and all of that will be automatically configured.

Additionally, you can use an environment variable to specify the
URL for any service, which will override all other configuration.
Added ability to list all grift methods
Version bump to 0.2.0
Regenerate gemspec for version 0.2.0