Add execute resource.
Merge pull request #12 from ryotarai/execute-resource

Add execute resource.
Add only_if and not_if options.
Add mail_alias resource
Update dependency on specinfra
Refactor Resources::Base#run.
Merge pull request #14 from mizzy/add-mail-alias-resource

Add mail alias resource
`recipient` option of `mail_alias` resource is always required.
Update README. (Thanks to @l15n)
Use Specinfra v2.0.0.beta30.
Don't call Specinfra.backend directory. Call Specinfra::Runner
Merge pull request #16 from mizzy/dont-use-backend-directly

Don't call Specinfra.backend directory. Call Specinfra::Runner
Rename Resources to Resource.
s/resources/resource/g
Use Specinfra.command.get.
s/option/attribute/g
s/option/attribute/g
s/option/attribute/g
Show diff.
Specify log level via command line option.