- [BREAKING CHANGE] Renamed and changed completion handler signatures…

… for **all**

  operations. They are now called `completionHandler` instead of `xxxxCompletionHandler`.
  Their signature is now `(response:[String:AnyObject]?, httpInfo:HttpInfo?, error:ErrorProtocol?) -> Void`.
- [IMPROVED] Error objects generated by the library now contain more information
  such as HTTP status code and the response received.
- [FIX] Fixed issue where the user agent wasn't being generated correctly.
- [FIX] Fixed issue where the `Content-Type` header was not being set correctly.
- [FIX] Fixed issue where a `DatabaseOperation` subclass would pass validation
   when the database name was not set.
- [FIX] Fixed issue where the session cookie was not created/set for requests to
   a protected CouchDB instance.
- [IMPROVED] Simplify operation subclasses processing responses in `CouchOperation`
- [NEW] New Hook for operations subclasses to perform additional actions such
   as a handler for each row in a view response.
- [NEW] New `QueryViewOperation`, to query CouchDB views, see the class documentation
  for usage.
- [NEW] New hook for operation subclasses, `serialise`, for usage see method documentation.

Initial Release