Migrating from travis-ci legacy infrastructure

[daniellawrence]

I noticed some failed tests during https://github.com/couchbase/couchbase-python-client/pull/29, this results in green builds for me.

Summary of changes are below...

see here: https://docs.travis-ci.com/user/migrating-from-legacy/

• Remove requirements for sudo
• Start testing python 3.4 and 3.4
• Allow twisted install to fail, it will on python2.6
• Remove quiet flag from pip install (for future debugging)

[mnunberg]

I've migrated to the new travis infrastructure several weeks ago. You can close this PR.