fix last seen

fix last seen using AuthService's promise which retrieves userProfile
switch to filtered collections

- use filtered collections pattern similar to broadcast controller
- add show all button
add number of activities and bugfix

changed objectLength filter to differentiate between object and array
because otherwise number returned may be 3 higher than correct (the
functions in an angularFireCollection are counted - not desirable)
bugfix and cosmetic change
remove unnecessary code
switch from filteredActivities object to array
Merge pull request #9 from reebalazs/activity_stream2

Activity stream improvements