LSMR-20: made migrate_momdb_to_lsmr.py executable. added it as bin script to cmake. use DBCredentials module for mom credentials

SW-381: Finally merged SW-381 back to LSMR-epic after merging with --record-only on SW-381 branch. Commit does look messy now

This makes the test pass again.

Reminder for myself:
Mocking is odd and does not follow common sense.  When I want to mock out a
function joe that is imported into foo.bar like this:
from there.here.willy import joe
then I have to mock it like so:
@mock.patch("foo.bar.joe")

Common sense would tell to mock it like so:
@mock.patch("there.here.willy.joe")

Task LSMR-20: Added an initial script that migrates projects (as projects) and related observations and pipelines (as tasks) from mom to lsmr. Still incomplete.

Task LSMR-23: Added remakemigrations.py script to conveniently remake migrations from scratch without manual action for subversion and choice population

Task LSMR-23: Added lsmr_makemigrations command to conveniently remake migrations from scratch without manual action for subversion and choice population

Task LSMR-14: Full specification model test coverage (DB and API) including tests for missing relations

Task LSMR-14: Functional test coverage of all models. Still missing some checks for missing relations.

Task LSMR-14: Added missing properties and altered relation attributes to match the current spec by the architect