Clean up token-swapping logic

Fixes #9
Fixes aptible/dashboard.aptible.com#62
Clean up Controller mixin

Fixes aptible/dashboard.aptible.com#62
Rubocop fixes
Bump version
Allow Rails to be started before/independently from auth server

Fixes #16
Allow gem client to decide when to call ensure_auth_key
Add ephemeral session cache functionality
Some additional session_cache functionality
Get rid of SessionCache

We can use Garner instead for all use cases. This reverts
* df76f45c066f15879a3d118df8b84dd273152f17
* bd5c3a0f343c6d404ca91765a3dd3253d6e8f05a
Merge pull request #17 from fancyremarker/launch-checklist-fixes

Changes to support Dashboard refactor, Part I