This cuts about 6 seconds off of the test startup time on my laptop.
The other startup costs are about 1 second for the server to come up
and about half a second for casperjs to begin executing tests.
generate-fixtures now takes a '--force' option that can be use to
force a regeneration of the test database.
(imported from commit 1f473507502f0edf159b2638abb392d9357eb46f)