fixed bitbucket-activity.coffee to recent api datastructure

Before:
[04/16/13 17:39 -> k9ert] [object Object] 
[04/16/13 17:23 -> MMGJ] [object Object]

Now:
[04/16/13 17:39 -> k9ert] some commitMessage here 
[04/16/13 17:39 -> k9ert] some other commit-message here
[04/16/13 17:23 -> MMGJ] yet another here