add ruby version to gemfile
Allow for size option in gravatar_for helper method
add remember token to user
update model tests
add user methods for remember token generation
authentication based front end tests
session controller for creating and destroying sessions
helper methods for determing whether users are signed in and current user
include session helper in application controller
use sign_in helper method on user create
signup, signin, signout route and sessions resource
sign in form
condition header items based on if user is signed in
Merge branch 'feature/user-sessions' into develop

* feature/user-sessions:
  condition header items based on if user is signed in
  sign in form
  signup, signin, signout route and sessions resource
  use sign_in helper method on user create
  include session helper in application controller
  helper methods for determing whether users are signed in and current user
  session controller for creating and destroying sessions
  authentication based front end tests
  add user methods for remember token generation
  update model tests
  add remember token to user
shoulda matchers gem for testing
oj gem for JSON parsing
sequence email to avoid validation issues
add support method to alias JSON.parse
initial tests for user request api
initial route setup for api endpoints