Respond to /repos.xml with CC XML

See #47
Fix up matcher to account for change in data structure

Aggregate CC XML would have a different output
Remove superfluous ivar
Cast ActiveRecord::Relation into an Array
Indent comment to match logic level
Cast in matcher as well

To match the previous change with the responder.
Fix grammar in spec description
Eschew questionable use of `File.join`

For constructing a URL, `File.join` is inappropriate.
Add missing closing </Project> tag
Fix closing tag
Merge pull request #99 from travis-ci/ha-api-gh47-aggregate-cc-xml

Respond to /repos.xml with CC XML