Octokit::UnprocessablEntity error on add_new_labels(...) in configuration.rb

Hi

I'm getting the following on trying to sync some repositories when it gets to add_label.

Ruby: 2.0.0p195 (2013-05-14 revision 40734) [x86_64-darwin11.4.2]
Octokit: 1.24.0

Error:
````
$ octoherder -i ssss.yml -u xxxx -p xxxxx
Label: "0 - Backlog"
#<Hashie::Mash documentation_url="http://developer.github.com/v3" errors=[#<Hashie::Mash code="invalid" field="color" resource="Label">] message="Validation Failed">
/Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octokit-1.24.0/lib/faraday/response/raise_octokit_error.rb:22:in `on_complete': POST https://api.github.com/repos/WebsandHQ/websand-import/labels: 422: Validation Failed:  (Octokit::UnprocessableEntity)
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/faraday-0.8.7/lib/faraday/response.rb:9:in `block in call'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/faraday-0.8.7/lib/faraday/response.rb:63:in `on_complete'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/faraday-0.8.7/lib/faraday/response.rb:8:in `call'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/faraday_middleware-0.9.0/lib/faraday_middleware/request/encode_json.rb:23:in `call'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/faraday-0.8.7/lib/faraday/connection.rb:247:in `run_request'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/faraday-0.8.7/lib/faraday/connection.rb:112:in `post'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octokit-1.24.0/lib/octokit/request.rb:64:in `request'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octokit-1.24.0/lib/octokit/request.rb:29:in `post'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octokit-1.24.0/lib/octokit/client/labels.rb:40:in `add_label'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octoherder-0.1.dev/lib/octoherder/configuration.rb:91:in `block in add_new_labels'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octoherder-0.1.dev/lib/octoherder/configuration.rb:89:in `each'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octoherder-0.1.dev/lib/octoherder/configuration.rb:89:in `add_new_labels'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octoherder-0.1.dev/lib/octoherder/configuration.rb:68:in `block in update_labels'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octoherder-0.1.dev/lib/octoherder/configuration.rb:67:in `each'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octoherder-0.1.dev/lib/octoherder/configuration.rb:67:in `update_labels'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octoherder-0.1.dev/lib/octoherder/cli.rb:61:in `run'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octoherder-0.1.dev/lib/octoherder/cli.rb:46:in `run'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/gems/octoherder-0.1.dev/bin/octoherder:10:in `<top (required)>'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/bin/octoherder:23:in `load'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/bin/octoherder:23:in `<main>'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/bin/ruby_executable_hooks:15:in `eval'
	from /Users/alex/.rvm/gems/ruby-2.0.0-p195/bin/ruby_executable_hooks:15:in `<main>'
````

I'm not sure whether it's a Gihub API <-> Octokit version issue, or something else.  Looking forward to getting this tool going!

Thanks!