add a minimize button to filebrowserdialog
improve server status refresh

Refresh more often for servers that are not connected yet
set initial server statuses to unconnected
rename and delete action no longer force a refresh

fix a regression of sharelink/delete/rename
Merge pull request #295 from haiwen/patch-28-no-refresh-after-rename

rename and delete action no longer force a refresh
Merge pull request #291 from haiwen/patch-25-add-minimize-button

add a minimize button to filebrowserdialog
updated seafile_en.ts
[qt5] initial work
build with qt5 as default with osx only
remove unused support functions since retina support is complete after qt5.2