updating the way we store docker image tags on repo scratchpad so that there are no mongo errors for having '.' in the key
updating importer plugins and tests for new image tag format
updating docker distributor for updated storage of tags
updating cud admin extensions and unit tests for updated tag format
updating image admin extensions and unit tests for updated tag format
updating tech-reference docs for updated way to store tags on the scratchpad
few more unit tests
adding myself to AUTHORS file and correcting minor typos
Merging master and resolving conflict
Merge pull request #25 from pulp/skarmark-docker-tags

Updated the way we store docker tags on repo scratchpad and all related distributor, importer and cli functions so that docker tags with '.' in it are supported