Add configuration for Travis-CI.

Travis CI is a hosted continuous integration service.
Remove twisted from pyflakes targets.
Address incompatibility with Twisted 12.3.0.

This resolves a clash in private attribute names.
Adjust API version for the Streaming API endpoints.

Twitter has harmonised the version numbers of the Streaming API
endpoints so that they are all numbered 1.1. All previous endpoints have
been deprecated and will stop working Real Soon Now™.

This partially addresses #15.