Add typhoeus 0.5 dependency.

Typhoeus doesn't add the Faraday adapter used in
Travis::Client::Session until version 0.5.0, so the CLI won't run with
an older version.
Merge pull request #65 from benmanns/typhoeus-dependency-update

Add typhoeus 0.5 dependency.
Fix typo in readme
Merge pull request #66 from pull-requests/fix-readme

Fix typo in readme
fix typo in rakefile