fixed querying bug to search similar names

fixed the bugs like [Dropdown doesn't hide when have more usernames with the same beginning](https://github.com/jakiestfu/Mention.js/issues/15) or [Typeahead does not hide when using with queryBy name/username](https://github.com/jakiestfu/Mention.js/issues/13)

to fix this, i change the code to only search for the word between user's cursor in textbox/inputbox and the space or delimiter character behind it. add this to last changes i made into the code to have different delimiter character for each user object, i added an `delimiters` option which is optional and defines all the possible delimiters. read the fuul documentation [here](https://github.com/bijanebrahimi/Mention.js)

CHANGELOG

* added overriding delimiter
* optional key/name/image object variable name 
* removed already mentions objects from emptyQuery list result
* fixed unclosed mention menu bug
* enhanced query results
* added versioning