Configuration files written in YAML

Maybe is YAML an option for the configuration files?

I also fixed a couple of bugs.

 * Fixed DoormanError, it raised an exception
 * Implemented a YAML configuration parser.
 * Configuration checker, which checks for (basic) syntax and if all files mentioned in the config exist.
 * Made --secret standard instead of --unsecret and made -s and -u mutually exclusive.
 * Using appdirs to find the config directory.
 * Using logging to print to the console and the -v or --verbose argument to log everything.
 * Test everything
 * Coverage report in Makefile

### Example configuration

    # social accounts
    /home/user/twitter.rb:
     twitter_passowrd: bHc0yz
     private_key: 1VpzKbLDTqC1vXb
    /home/user/pythoncodes/githubapi.py
     github_password: wKJ4cV

    # secret text
    /etc/secret.conf:
     my_secret: really secret thing

    # secret function
    ../settings/my_settings.py:
     my_func: [i for i in others if i < 3]