Remove cache if change profile pic, change list privacy label, update collaborators preview width, change duration string

a few things

Remove cache whenever user changes profile pic (i think for other users, cache after certain time)
- test it works by changing profile pic
Change list privacy label to "Public" and "Private"
Update collaborators preview view width after collaborators added/removed
Change duration string to be in hour and minute

flickchicks / flick-ios