Allow colon inside tag name
One example where colons are useful is when implementing debtags-like tags
(Faceted Classification). For example:
isa::bug
isa::rfe
severity::high
severity::low
The double colon here makes it easier to recognize the fact that Faceted
Classification is being used.
Related to https://pagure.io/pagure/issue/3406
Merges https://pagure.io/pagure/pull-request/3458