CYB-50 Adding API infrastructure.  Enscapsulates all calls to the Canvas API in this new class

  * Uses Faraday & Net::HTTP::Persistent (keeps connections open, to save setup/teardown)
  * Requires setup in config/secrets.yml with API keys from Canvas (see README.md)
  * Some specs do actual calls, so for them to run it requires an instance of Canvas.
  * Some rewrite on README.md
CYB-50.  Don't delete bootstrap, remove rudundant spec, use I18n value for User-Agent.
CYB-50.  Fix typo in README.md
Merge pull request #9 from coyote/make_api_calls

CYB-50 Adding API infrastructure.  Enscapsulates all calls to the Canvas...