Add local_docker facility for bind-mounting ca-trust

This implements one possible solution for #411, but does not solve it for
Kubernetes or Openshift installations.

# Conflicts:
#	installer/inventory

installer/inventory

@@ -100,4 +100,4 @@ pg_port=5432
 # this variable causes this directory on the host to be bind mounted over
 # /etc/pki/ca-trust in the awx_task and awx_web containers.
 # NOTE: only obeyed in local_docker install
-#ca_trust_dir=/etc/pki/ca-trust
+#ca_trust_dir=/etc/pki/ca-trust

installer/local_docker/tasks/standalone.yml

@@ -79,7 +79,11 @@
     state: started
     restart_policy: unless-stopped
     image: "{{ awx_web_docker_actual_image }}"
-    volumes: "{{ project_data_dir + ':/var/lib/awx/projects:rw' if project_data_dir is defined else omit }}"
+    volumes: >
+      {{
+        [project_data_dir + ':/var/lib/awx/projects:rw' if project_data_dir is defined else []
+        + [ca_trust_dir + ':/etc/pki/ca-trust:ro'] if ca_trust_dir is defined else []
+      }}
     user: root
     ports:
       - "{{ host_port }}:8052"
@@ -113,7 +117,11 @@
     state: started
     restart_policy: unless-stopped
     image: "{{ awx_task_docker_actual_image }}"
-    volumes: "{{ project_data_dir + ':/var/lib/awx/projects:rw' if project_data_dir is defined else omit }}"
+    volumes: >
+      {{
+        [project_data_dir + ':/var/lib/awx/projects:rw' if project_data_dir is defined else []
+        + [ca_trust_dir + ':/etc/pki/ca-trust:ro'] if ca_trust_dir is defined else []
+      }}
     links: "{{ awx_task_container_links|list }}"
     user: root
     hostname: awx