chore (gruntfile/docs):

* Adds grunt-repos task to pull down a list of assemble repos, which is then used by grunt-readme (and passed to the templates as context)
* Adds grunt-prettify task in lieu of using an assemble plugin for prettifying the generated HTML (and since it was slowing down the build too much)
delete tag created by grunt-release
Merge commit '6c9451ecedf841ca54bb6033cc3a1979d796a64f'