Allow JTs to specify and prompt for SCM branch

Copy project folder each job run
  change cwd to private_data_dir, from proj
  do not add cwd to show_paths if it is
  a subdirectory of private_data_dir, which
  is already shown

Pass the job private_data_dir to the local
  project sync, and also add that directory
  to the project sync show paths

Add GitPython dep and use for job sync logic
  use this to manage shallow clone from desired
  commit, and to map branch to commit,
  and to assess necessity of project sync

Start on some validation change, but not all
  allow arbitrary playbooks with custom branch

requirements/requirements.in

@@ -22,6 +22,7 @@ django-split-settings==0.3.0
 django-taggit==0.22.2
 djangorestframework==3.9.4
 djangorestframework-yaml==1.0.3
+GitPython==2.1.11
 irc==16.2
 jinja2==2.10.1
 jsonschema==2.6.0

requirements/requirements.txt

@@ -40,6 +40,8 @@ djangorestframework-yaml==1.0.3
 djangorestframework==3.9.4
 
 future==0.16.0            # via django-radius
+gitdb2==2.0.5             # via gitpython
+gitpython==2.1.11
 hyperlink==19.0.0         # via twisted
 idna==2.8                 # via hyperlink, requests, twisted
 incremental==17.5.0       # via twisted
@@ -100,6 +102,7 @@ service-identity==18.1.0  # via twisted
 simplejson==3.16.0        # via uwsgitop
 six==1.12.0               # via ansible-runner, asgi-amqp, asgiref, autobahn, automat, cryptography, django-extensions, irc, isodate, jaraco.classes, jaraco.collections, jaraco.itertools, jaraco.logging, jaraco.stream, pygerduty, pyhamcrest, pyopenssl, pyrad, python-dateutil, python-memcached, slackclient, social-auth-app-django, social-auth-core, tacacs-plus, tempora, twilio, txaio, websocket-client
 slackclient==1.1.2
+smmap2==2.0.5             # via gitdb2
 social-auth-app-django==2.1.0
 social-auth-core==3.0.0
 sqlparse==0.3.0           # via django