Fix #307 TestParsePersonaAssertion failed

* Create EmailSite class to store email and site information

* Instead of using a list of strings, using EmailSite object as a key to store assertion in the assertions dictionary
Fix #307 Rework with a simpler solution

Use 'Email:Site' string as a key instead of the EmailSite custom class.
Merge pull request #313 from couchbaselabs/issue-307

Fix #307 TestParsePersonaAssertion failed