Issue #17 and adding myself to an authors list in about.html

Issue #17:
- now generateNewShort() method returns guaranteed unique short url
- it is significantly faster to use find() + limit() because findOne() will always read + return the document if it exists. find() just returns a cursor (or not) and only reads the data if you iterate through the cursor (http://blog.serverdensity.com/checking-if-a-document-exists-mongodb-slow-findone-vs-find/).
- I think it could be made easier
- I want a code review
- and...ok, i now this is really bad, but i don't test it. sth wrong on my side with building project and mongodb authorization :(

about.html:
- adding myself to an authors list
- change "main developer" to "Team lead"..i think it's sound better (: