Few tid-bits of info about imported documents

while working on this feature we realised that
if an editor starts working through the list
using the speed tagging interface and leaves
it midway there's no way to see how far they
went ?

this tiny change will at least provide one
place where the importer can see how many
of the documents from this import were
moved to Draft and an ordered list will
give a sense of the import order.

it also helps test the story.
Add methods to Import to support Save and show next
Save and next button on speed tagging interface

also, making button text clearer and removing un-used id.
Setting misbehaving citizens right

took me a while to realize that the connection
my test transaction was running within was not
the connection Import uses. when running with
other tests, my test picked-up one of these
previously opened connections which we've
removed in this commit.

because ActiveRecord transactions are per-connection,
Import was totally oblivious of the data setup in my
test causing unexpected failures.
Merge pull request #1317 from alphagov/save_and_next_on_speed_tagging

Save and next on speed tagging