Jenkins.sh should set -e

So that it fails on any error, not just an error on the last line.
Merge pull request #175 from alphagov/jenkins_sh_set_e

Jenkins.sh should set -e
Drop test database before running tests.

To ensure tests run with a clean state - no stale data, indexes etc.

Also enabled autocreate_indexes for tests so that the model defined
indexes are created.
Enable pagination for the artefacts index

Now that the number of artefacts in the system has significantly
increased, this endpoint needs to be paginated to return results in a
timely fasion.
Return 500 items per page for the artefacts index

This is a good balance of page size to number of pages.  This results in
each page being around 90kB, and around 180 pages with the current data
set.
Use a batch insert to improve test performance
Merge pull request #177 from alphagov/artefacts_index_pagination

Paginate the artefacts index.
Add comment clarifying how indexes are handled
Fix the regex used to drop collections
Merge pull request #176 from alphagov/drop_test_db

Drop test database before running tests.