Squash all migrations (#365)

* Squash migrations: squash all migrations into a single, cleaned up migration step

* Remove no longer needed dependency jsonfield: had no longer been used in the actual code base but had still been a dependency because it was used in intermediate migration steps

Author: matzf

requirements.in

@@ -8,7 +8,6 @@ django-registration>=3.1
 graphviz
 gunicorn
 jinja2
-jsonfield
 psycopg2-binary  # PostgreSQL backend
 pynacl
 pyyaml>=4.2b1  # for fixtures and config generation; high severity vulnerability before 4.1 (CVE-2017-18342)

requirements.txt

@@ -94,7 +94,6 @@ django==3.1.6 \
     # via
     #   -r requirements.in
     #   django-registration
-    #   jsonfield
 graphviz==0.14 \
     --hash=sha256:cb0e878f90378489f17aab140b68e64e44b79e4cb59a530c8863d84bf2e2e5f5 \
     --hash=sha256:e104ba036c8aef84320ec80560e544cd3cad68c9f90394b4e2b87bc44ab09791
@@ -111,10 +110,6 @@ jinja2==2.11.3 \
     --hash=sha256:03e47ad063331dd6a3f04a43eddca8a966a26ba0c5b7207a9a9e4e08f1b29419 \
     --hash=sha256:a6d58433de0ae800347cab1fa3043cebbabe8baa9d29e668f1c768cb87a333c6
     # via -r requirements.in
-jsonfield==3.1.0 \
-    --hash=sha256:7e4e84597de21eeaeeaaa7cc5da08c61c48a9b64d0c446b2d71255d01812887a \
-    --hash=sha256:df857811587f252b97bafba42e02805e70a398a7a47870bc6358a0308dd689ed
-    # via -r requirements.in
 markupsafe==1.1.1 \
     --hash=sha256:00bc623926325b26bb9605ae9eae8a215691f33cae5df11ca5424f06f2d1f473 \
     --hash=sha256:09027a7803a62ca78792ad89403b1b7a73a01c8cb65909cd876f7fcebd79b161 \