update roadmap

- update with 1.6.1 and 2.0.0 released version
- update for 2.1.0 content and proposed released date according to iOS meeting:
http://transcripts.jboss.org/meeting/irc.freenode.org/aerogear/2014/aerogear.2014-10-21-14.00.txt 
- update for 2.2.0 content

@cvasilak @matzew @danbev mind a review?
for oauth2 resource owner credentials grant mainly, let me add main ticket as sublist