Add screenshot taking helper

Capybara hasn't released a gem with this ability yet.
Revert back to full repo access

* Hound cannot work without repo access because a collaborator cannot
* be added without it.
Add repo loading indication
Cache GitHub responses in memcached

https://trello.com/c/1qeitvaD/204-address-rate-limiting
Revert "Cache GitHub responses in memcached"

* Seeing an encoding exception on staging

  > Encoding::UndefinedConversionError: "\xE2" from ASCII-8BIT to UTF-8

This reverts commit 57f6f6372f418e9944440d7d98ad96c5d35dd151.
Add example keys for Hound to sample.env
Add Hound to repo team with admin access

* We discovered that `Octokit::Client#repo_teams` may return repo teams
* to which the current Hound user does not belong. When we attempt to
* add Hound to a team to which the current user does not belong,
* `Octokit::Client#add_team_member` returns false and
* `ActivationsController#create` returns a 502 status. This is causing
* some users to experience a "Repo failed to activate" error.
* In this commit:
  - Change logic in `GithubApi#add_user_to_org` so Hound is added to the
    first existing repo team with admin access to which the current
user belongs
  - Extract GithubUser class
  - Add user_teams.json fixture
  - Update existing tests and add feature spec
* https://trello.com/c/CX9NavUF
Fix typo in spec
Merge pull request #206 from chiastolite/patch-1

Fix typo in spec
move github_user require into spec
Remove duplicates
Merge pull request #212 from bry4n/patch-1

Remove duplicate method
Do not retry after octokit 404
Add Hound user to existing Services team

https://trello.com/c/4GfbD6J6/219-repo-fails-to-activate-when-services-team-already-exists
Refactor StyleChecker to add StyleGuide

Split out functionality of `StyleChecker`, and wrap RuboCop specifics into
`StyleGuide`. This simplifies `StyleChecker` and allows for easier testing of
default style guide rules.
Move StyleGuide to app/models
Notify Sentry when repo activation fails

https://trello.com/c/VcZ1JoDq/225-notify-sentry-when-repos-fail-to-activate
do not retry Octokit::Unauthorized
Add missing expectation
Use cached GitHub responses when 304 is returned

https://trello.com/c/1qeitvaD/204-address-rate-limiting