Implement WFJT prompting for limit & scm_branch

add feature to UI and awxkit

restructure some details of create_unified_job
  for workflows to allow use of char_prompts
  hidden field
avoid conflict with sliced jobs in char_prompts copy logic

update developer docs

update migration reference

bump migration

awx/main/migrations/0085_v360_WFJT_prompts.py

@@ -0,0 +1,59 @@
+# Generated by Django 2.2.2 on 2019-07-23 17:56
+
+import awx.main.fields
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('main', '0084_v360_token_description'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='workflowjobtemplate',
+            name='ask_limit_on_launch',
+            field=awx.main.fields.AskForField(blank=True, default=False),
+        ),
+        migrations.AddField(
+            model_name='workflowjobtemplate',
+            name='ask_scm_branch_on_launch',
+            field=awx.main.fields.AskForField(blank=True, default=False),
+        ),
+        migrations.AddField(
+            model_name='workflowjobtemplate',
+            name='char_prompts',
+            field=awx.main.fields.JSONField(blank=True, default=dict),
+        ),
+        migrations.AlterField(
+            model_name='joblaunchconfig',
+            name='inventory',
+            field=models.ForeignKey(blank=True, default=None, help_text='Inventory applied as a prompt, assuming job template prompts for inventory', null=True, on_delete=models.deletion.SET_NULL, related_name='joblaunchconfigs', to='main.Inventory'),
+        ),
+        migrations.AlterField(
+            model_name='schedule',
+            name='inventory',
+            field=models.ForeignKey(blank=True, default=None, help_text='Inventory applied as a prompt, assuming job template prompts for inventory', null=True, on_delete=models.deletion.SET_NULL, related_name='schedules', to='main.Inventory'),
+        ),
+        migrations.AlterField(
+            model_name='workflowjob',
+            name='inventory',
+            field=models.ForeignKey(blank=True, default=None, help_text='Inventory applied as a prompt, assuming job template prompts for inventory', null=True, on_delete=models.deletion.SET_NULL, related_name='workflowjobs', to='main.Inventory'),
+        ),
+        migrations.AlterField(
+            model_name='workflowjobnode',
+            name='inventory',
+            field=models.ForeignKey(blank=True, default=None, help_text='Inventory applied as a prompt, assuming job template prompts for inventory', null=True, on_delete=models.deletion.SET_NULL, related_name='workflowjobnodes', to='main.Inventory'),
+        ),
+        migrations.AlterField(
+            model_name='workflowjobtemplate',
+            name='inventory',
+            field=models.ForeignKey(blank=True, default=None, help_text='Inventory applied as a prompt, assuming job template prompts for inventory', null=True, on_delete=models.deletion.SET_NULL, related_name='workflowjobtemplates', to='main.Inventory'),
+        ),
+        migrations.AlterField(
+            model_name='workflowjobtemplatenode',
+            name='inventory',
+            field=models.ForeignKey(blank=True, default=None, help_text='Inventory applied as a prompt, assuming job template prompts for inventory', null=True, on_delete=models.deletion.SET_NULL, related_name='workflowjobtemplatenodes', to='main.Inventory'),
+        ),
+    ]