Addresses OpenSSL::Digest::Digest deprecation. https://github.com/progrium/ruby-jwt has been updated in master, but not released.
Travis workaround needed for testing ruby 1.8.7
Reverts: Travis workaround needed for testing ruby 1.8.7
https://github.com/twilio/twilio-ruby/pull/79#issuecomment-32962877
Merge pull request #79 from toreyheinz/master

Addresses OpenSSL::Digest::Digest deprecation.