Update to Elixir 0.14.0

Also deps and travis config
Fix websocket handler tests
Fix deprecation warning on GenEvent
Bump 0.2.0

[ci skip]
Update to Elixir 0.14.1
Update README.md

[ci skip]
Update to Elixir 0.14.2
Run Elixir 0.14.2 and 0.14.3 on Travis CI
Fix typespecs spotted by dialyzer
Add OTP 17.1 to run on Travis CI
Bump version and ensure support to ~> 0.15.0
Update deps and use hex package where possible
Use Logger instead of Lager
Do not mock :application
Drop support to 0.14.*
Run the app on test env
Fix integration test
Run integration test on Travis CI
Move environment configuration to config/config.exs
Use config/config.exs to define app env