Only accept attributes that are defined
Bump version of ldp to 0.0.5
Bump version to 0.0.9
Move host to class method.

Need this in order to have a single point of entry for override in
ActiveFedora's cleanup method.
Merge pull request #15 from terrellt/feature/HostClassMethod

Move host to class method.
merge
updated specs to remove rspec-core deprecations