stream_create: Make handlers more modular for users.
stream_create: Make handlers more modular for users.

We now wire up the handlers that correspond to elements in
the 'new_stream_users' template when we render that template,
rather than at startup time.

We also delegate the events only up to #people_to_add, rather
than all the way up to body/document.

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