Adding `tag' command: initial commit.
Added 'add' and 'remove' functionality.
Bug fixes.
Bug fixes (API requires request to be delivered in request_body)
Added redirect to config file.
Fix mime-type lookup.

refs #1813
Default redirect to workbench in production configuration to workbench.`hostname`
Complete `arv tag add' and `arv tag remove' support (fixes #1530)
Merge branch '1530-arv-tag-commands'