Instead of querying the existing mappings for overlap and either
updating or inserting depending on the result, we now delete
overlapping mappings first and then only insert.

This is roughly twice as fast. But of course still a horrible
setup compared to some kind of UPSERT functionality which is
unfortunately missing in current PostgreSQL.

Drop BatchJob.download_url column

This is now created on use, by #111.

Fixes #112

Drop TranscriptProteinLink database table

This data is now in Redis, by #94.

Fixes #95

Update requirements

Readable name for batch notification sender

Release 2.0.14

Made e-mail address optional in batch checker website interface.

This address is set with the new `BATCH_NOTIFICATION_EMAIL` config
setting and defaults to the value of `EMAIL`.

Fix counters reporting on about page

We forgot to include the description extractor in the totals. Also,
it said batch jobs were excluded from the totals, which is not the
case.

Log result id for finished batch job

Fix link in batch notification if submitted from webservice

Link to mapview examples Gist

Update Mailcheck

Use Mailcheck in the batch jobs form

This enables attachement of these handlers to elements that are
added to the DOM later as opposed to being in the original source
HTML.