Added new form to create subtitles (#1121)

There's a lot more to do, but this is a basic starting point.  The
form handles what the old closure dialog code used to do when the user
clicks the create subtitles link.
Fixes for the create subtitles language select box

Don't allow languages that already have subtitles.  Put the user's
preferred languages on top.
Simplify template logic

Now that we're using the new editor, we don't need can_create_trans.
Style the create subtitles dialog like the editor dialogs

Added a _form_field_table.html template.  Updated v1.css with some
stuff copied from the editor css.

Messed around with the header styling.  Hopefully it looks okay.
Moved dialog to its own template.

This will make it easier to include on other pages.
Changed the widget code to use the new dialog.

Added a function to Site to open dialogs.
Made the form work on the language pages

Added convenience method that handles everything required for the
CreateSubtitlesForm.  Since that form is going to be on multiple
pages, I figured it's nice to have.

Don't update the video view counter for form posts.
Added test for the CreateSubtitlesForm

Fixed exception when creating the form for an anonymous user.
Updated team dashboard page to use the new editor

Removed code to add the widget settings.  The new system just uses a
regular modal form.
Added button to switch to the legacy editor from the new one.

Removed buttons to switch to the legacy editor after save or exit.
Created form for subtitle tasks with no language set.

This handles the case where we link to the task, but we can't send the
user directly to the editor because we need to set the language for
the task (and also possibly the primary audio language code for the
video).
Refactored create subtitles form.

Generalized the DashboardCreateSubtitlesForm as
MultiVideoCreateSubtitlesForm.  The new code handles the same stuff as
the old one, plus it:
  * Disables the input for primary audio language if it's already set.
  * Disables the select options for languages that are already
  created.

Moved common code from CreateSubtitlesForm and
MultiVideoCreateSubtitlesForm into a base class.

Added CSS styles for disabled inputs for our forms.

Updated forms tests a bit.  Refactored templates a bit.
Replaced task links on the dashboard and tasks pages

Made team forms that subclass CreateSubtitlesForm and
MultiVideoCreateSubtitlesForm, and also handle tasks.
Made Edit Subtitles link on the language page load the new editor
Fixed task links on the user profile page
Removed "This video doesn't have any subtitles yet" text

We were showing it all the time, regardless of the status of the
subtitles.  Like I said in 1121, I don't think we need this text at
all anymore.
Merge remote-tracking branch 'origin/staging' into gh-1121
Removed new editor admin links

The new editor is the default now, so we don't need that special link.
Fixed legacy editor link
Fixed link text for the tasks page

I think the old logic was that we would use "Resume" if
get_subtitle_version() returned a version and if the task was assigned
to the user.

The new logic is to use "Resume" if the asignee is set.  I think this
should work fine.  get_subtitle_version() would return versions for
translation tasks before the user created a version, so we shouldn't
use that check.  The user should only see the task if it's assigned to
them or not assigned at all, so the assignee check should be the same
as before.