feat(tagsInput): add callback option for invalid-tag event

This pullrequest adds the option for developers to specify a callback
that gets triggered whenever a tag is invalid. This makes it easier
for developers to add custom event handlers for this event.
feat(tags Input): add support for pasting a collection of tags

This pullrequest adds functionality that allows a user to paste a
separated string instead of having to type all entries manually. the
pasted string will be parsed to tags and the invalid ones will be
discarded. The separators can be defined with the separatorList
attribute
Merge branch 'featInvalidTagCallback'

Conflicts:
	src/tags-input.js