Fix cli api_check

It was loading the wrong config file, namely the test config.
Added basic rails 4 support
Set config using ENV variables instead of a config file
Use RAILS_ENV when loading config from env
Merge pull request #81 from 80beans/api_check

[MERGE] Fix cli api_check
Merge pull request #83 from 80beans/set_config_using_env

[MERGE] Set config using ENV variables instead of a config file
Fix for rails 4 session object
Raise log level to debug when set in the config
Unify AppSignal.logger message format
Merge pull request #85 from 80beans/improve_logger

Improve logger
Bump to v0.5.4 [ci skip]
Allow failures in 1.8.7
Use ActiveSupport::JSON, and deflate post requests
Check existence of logger method
Merge branch 'develop'
Bump to v0.5.5 [ci skip]
Push tags and master to public and private repo
Update gem homepage
Point the gem page to the correct page
Bump to v0.5.4 [ci skip]