Config and YAML

[jcf]

Hi Nick,

I've forked sheepsafe and changed a couple of things I thought you might be interested in. Here's a summary of what's in this pull request:

• I've changed the message that gets logged when ~/.sheepsafe can't be found to use the same path as the one in SheepSafe::Config::FILE
• Use YAML.load_file when reading the config file
• Replace the use of the @config instance variable in #write with a call to the #config attribute reader, which is used elsewhere in Config already.

All the tests are passing. I have another pull request I'm about to send but I'm not sure you'll want these changes in your master branch.

[nicksieger]

Looks good, thanks.