Upgrade to Crystal 0.12.0 (YAML.parse)

[cjgajard]

Breaking change on Crystal 0.12.0 (2016-02-16):

YAML.load was renamed to YAML.parse, and it now returns a YAML::Any.

$ crystal build src/guardian.cr --release
Error in ./src/guardian.cr:167: instantiating 'Guardian::Watcher:Class#new()'

Guardian::Watcher.new
                  ^~~

instantiating 'Guardian::Watcher#initialize()'

in ./src/guardian.cr:32: undefined method 'load_all' for YAML:Module

        YAML.load_all(File.read(file)).each do |yaml|
             ^~~~~~~~

[f]

Thanks!

[cjgajard]

Thanks for merging 😄