This change was inspired by the problem of translators needing to
translate "Subscribe" to languages that use different forms depending
on the identity of the noun being subscribed. In most places in the
app, a button with that as the entire label should be translated in
the "subscribe myself" form; but in this one it should be "subscribe
someone else".
Thinking about this, the current label is a bit misleading in English
for someone who ignores the error message text and just reads the
button, so the best fix is to just change the string, which of course
also makes things unambiguous for translators as well.
This commits add data-stream-id attribute to the compose_invite_users
template. This helps in avoiding the error that occured if user
clicked the link after renaming of stream.
As a result of above changes, the checks for empty and invalid stream
name in compose box are done in warn_if_mentioning_unsubscribed_user
function instead of needs_subscribe_warning function.
This commit changes the compose_invite_users template to use
data-user-id as property intead of data-useremail.
This is changed to maintain consistency with other parts of the
code where user_ids are used for referring to users.
This also helps in removing some of the checks for the case of
undefined emails.