Rename `grails` repository to `dbunit-operator`

Hi Mike,

Thanks you for your plugin!
I found that your repository name is not a best way to name it. 
It named `grails` that can confuse users who can think that it contain Grails itself.
But inside it has another subfolder `dbunit-operator`.
I would like to propose you rename repository to `dbunit-operator` and move all contents of folder dbunit-operator up to root folder.
This pull request already contains moving dbunit-operator contents, just apply it.
But rename of repository you should do yourself in its settings.