Changes for Tower virtualenv support

* Break requirements down into ansible and tower reqs
* Generate separate Ansible and Tower virtual environments
* Install appropriate requirements files into each one
* Modify development tools to use these venvs instead of our old
  site-packages
* Modify settings to indicate venv enablement and location of venvs
* Modify tasks to use the proper virtual environment for its purpose

awx/settings/production.py

@@ -41,6 +41,14 @@ JOBOUTPUT_ROOT = '/var/lib/awx/job_status/'
 # The heartbeat file for the tower scheduler
 SCHEDULE_METADATA_LOCATION = '/var/lib/awx/.tower_cycle'
 
+# Ansible base virtualenv paths and enablement
+ANSIBLE_USE_VENV = True
+ANSIBLE_VENV_PATH = "/var/lib/awx/venv/ansible"
+
+# Tower base virtualenv paths and enablement
+TOWER_USE_VENV = True
+TOWER_VENV_PATH = "/var/lib/awx/venv/tower"
+
 LOGGING['handlers']['tower_warnings'] = {
     'level': 'WARNING',
     'class':'logging.handlers.RotatingFileHandler',