MUC: do not add yourself to the muc user list.
add an listener for the muc roster update.

this is for the ConferenceDetailsActivity to show
precence updates immediately.
Update german translations
MUC: option to set/delete bookmark in conference details.
Merge pull request #712 from kriztan/patch-2

Update german translation
Merge pull request #714 from betheg/muc_bookmark_cd

MUC: option to set/delete bookmark in conference details.
Merge pull request #713 from betheg/muc

MUC: do not add yourself to the muc user list.