Fix issue when resolving a stack output value
Don't always add the stackname to the source stack

If you need to look up a value from a stack defined outside of cumulus you
don't want anyting prefixed to the stackname. By placing a - at the start of the stackname
it is not prepended to.
Stack-level tags support
'disable' directive
Merge pull request #2 from deanwilson/master

Don't always add the stackname to the source stack
Merge branch 'master' of github.com:cotdsa/cumulus
Update README.md