If minChars===0 then show all results immediately

This is a port of a patch made from https://github.com/coderow/jquery-tokeninput (a year ago) which has not been merged with the mainline repo for this project.  The patch ported is 29bb94f6f8c3739992c285be9e645e7f2301d74c.

See:
https://github.com/coderow/jquery-tokeninput/commit/29bb94f6f8c3739992c285be9e645e7f2301d74c