yaml for .licenserc format

[bengl]

YAML makes it much easier to define the file format, and enables tool authors to use existing YAML libraries to parse.

As far as I can tell, YAML is compatible with the format you had already described.

[kemitchell]

@bengl, thanks again for good commentary.

I considered YAML, as well as JSON and INI, before settling on just stating the format in the spec. While YAML is very nice to read, it's also a large spec with lots of native datatypes and alternative syntax. I hesitate to bring all that in when parsing as described is so trivial.

I don't suppose there's anything stopping anyone with a YAML parser handy from noticing that the syntax is a subset. I'd be tempted to implement a Ruby parser that way.