Database checks happen before installing pip requirements

[jnm]

I think this only affects developer mode.

kobo-install/helpers/upgrading.py

Lines 45 to 51 in 693189c

	CLI.colored_print(
	'Waiting for PostgreSQL database to be up & running...',
	CLI.COLOR_INFO)
	frontend_command = kpi_run_command + _kpi_db_alias_kludge(' '.join([
	'python', 'manage.py',
	'wait_for_database', '--retries', '45'
	]))

Consider this situation:

1. Version abc123 of kpi depends on formpack version alpha_uno;
2. I build kpi using this code and have a great time;
3. I check out version def456 of kpi, which depends on formpack version beta_five;
   • kpi def456 imports SUPER_GOOD_STUFF constant from formpack beta_five;
4. I try to restart my environment;
5. The call to manage.py (see link above) now fails because the last-built image (and hence my new kpi container) still has formpack version alpha_uno, which doesn't have the SUPER_GOOD_STUFF constant.

Before I added these manage.py database checks, I think the kpi container would've started normally and automatically installed the new beta_five version of formpack, without having to rebuild the kpi Docker image.

cc @p2edwards