Update link to knife-solo home page
Rename ec2debian-build-ami to build-debian-cloud
Rename the plugin to "debian-cloud-chef"

As the main project has been renamed to build-debian-cloud to reflect
the fact it is not only tight to EC2, we also rename our plugin.
There is nothing EC2 specific and the plugin should work with all
providers.
Merge pull request #1 from tmatilai/project-renames

Rename the plugin to "debian-cloud-chef"