refactored cloud-view and added starred/activities tab
refactor repo refresh code to repo-service
prompt download the library when clicking starred file
handle double click on a starred file
only show drop area under repos tabs
added icons for different file types
fixed tooltip of starred files list
resize tabs images to 24px
use darker file icons
fixed starred files tab width
updated tabs icon
WIP: added activities tab
handle loading more events
fixed handling urls with query params in CertsManager

When a QUrl has query params, its toString() member function would
include these params in the string representation, which we don't
want.
WIP: use Qt MVC to present activities
load user avatars in activities
make activities avatars round
donnot highlight repo category item when selected
separate local avatar files for different accounts
show current account avatar