Update gemspec.
Update to ruby 2.0.
Add rubocop todo.
Rubocop: Multiline blocks should use do/end.
Remove redundant hashes around parameters.
Added module documentation.
Remove extra blank line.
Use the ruby 1.9 hash syntax.'
Use percent literal delimiters.
Reduandant self.
Use  instead of  to signal exceptions.
Formatting.
Improve formatting.
Use %w for array of words.
Ignore method length for Client#prepare_parallel_request.
Line length of Client class.
Line length of Utils class.
Line length.
Line length for mixpanel_client_spec.
Fix remaining line length offences.