tag support for vs create / edit

Adds the ability to specify tags both on the vs (aka cci) create
instance CLI / call as well as modify tags on the edit CLI / call.
Additionally this PR supports tags w/r/t exporting templates and create
using the --like option. Finally unit tests are included.

implements https://github.com/softlayer/softlayer-python/issues/354
The line, "Use the empty string to remove all tags." doesn't make sense in the context of creating a new instance.