Merge pull request #19 from hcchien/master

add some avatar for the speakers
CHANGE: clean RKajiyama twitter avatar
Change user nickname.
Merge pull request #20 from appleboy/develop

Change user nickname.
NEW: add RKajiyama avatar
NEW: add appleboy to participant.yml
Update appleboy avatar.
Merge pull request #23 from appleboy/patch-1

Update appleboy avatar.
Change othree's name to upside down character
Merge pull request #24 from othree/master

Change othree's name to upside down character
Added freak self intro.
Added more description about expertise in Ruby.