Merge pull request #13 from nabetama/groups

Groups
Merge pull request #14 from nabetama/groups

Groups
Merge pull request #15 from nabetama/groups

GroupsInvite
Merge pull request #16 from nabetama/groups

Groups
ImList
im fixup
ImHistory
Moved.
ImMark
ImOpen
Update gitignore.
Merge pull request #17 from nabetama/im

Im
OauthAccess
Merge pull request #18 from nabetama/oauth

OauthAccess
PresenceSet
Merge pull request #19 from nabetama/presence

PresenceSet
Rtm
[Api document](https://api.slack.com/rtm)
Merge pull request #20 from nabetama/rtm

Rtm
websocet
Add a comment to Rtm.