upload: Add/enable `uploadStarted` option in jquery-filedrop plugin.
upload: Add/enable `uploadStarted` option in jquery-filedrop plugin.

We were missing it but it is added in the upstream, so just added it
at the appropriate place in plugin code(in the upstream there is some
code refactoring but this seems to be the most appropriate place).

brainwane/zulip,showell/zulip,rht/zulip,rht/zulip,brainwane/zulip,punchagan/zulip,shubhamdhama/zulip,rishig/zulip,eeshangarg/zulip,rht/zulip,rishig/zulip,andersk/zulip,kou/zulip,dhcrzf/zulip,showell/zulip,hackerkid/zulip,hackerkid/zulip,jackrzhang/zulip,synicalsyntax/zulip,dhcrzf/zulip,tommyip/zulip,eeshangarg/zulip,synicalsyntax/zulip,kou/zulip,andersk/zulip,punchagan/zulip,hackerkid/zulip,synicalsyntax/zulip,kou/zulip,tommyip/zulip,andersk/zulip,rht/zulip,zulip/zulip,brainwane/zulip,jackrzhang/zulip,rishig/zulip,showell/zulip,rht/zulip,eeshangarg/zulip,rishig/zulip,zulip/zulip,dhcrzf/zulip,jackrzhang/zulip,punchagan/zulip,shubhamdhama/zulip,punchagan/zulip,zulip/zulip,zulip/zulip,timabbott/zulip,shubhamdhama/zulip,rishig/zulip,shubhamdhama/zulip,showell/zulip,zulip/zulip,andersk/zulip,synicalsyntax/zulip,tommyip/zulip,dhcrzf/zulip,tommyip/zulip,synicalsyntax/zulip,brainwane/zulip,brainwane/zulip,rishig/zulip,timabbott/zulip,jackrzhang/zulip,kou/zulip,brainwane/zulip,hackerkid/zulip,jackrzhang/zulip,rht/zulip,tommyip/zulip,punchagan/zulip,hackerkid/zulip,rishig/zulip,dhcrzf/zulip,jackrzhang/zulip,brainwane/zulip,kou/zulip,timabbott/zulip,shubhamdhama/zulip,shubhamdhama/zulip,timabbott/zulip,showell/zulip,eeshangarg/zulip,tommyip/zulip,timabbott/zulip,synicalsyntax/zulip,showell/zulip,zulip/zulip,synicalsyntax/zulip,jackrzhang/zulip,timabbott/zulip,punchagan/zulip,dhcrzf/zulip,andersk/zulip,dhcrzf/zulip,eeshangarg/zulip,kou/zulip,hackerkid/zulip,zulip/zulip,tommyip/zulip,eeshangarg/zulip,kou/zulip,andersk/zulip,eeshangarg/zulip,showell/zulip,hackerkid/zulip,timabbott/zulip,andersk/zulip,rht/zulip,punchagan/zulip,shubhamdhama/zulip