Add scripts/instack-prepare-discovery

Test as:
TFTP_ROOT=/tmp/tftp IRONIC_URL=http://127.0.0.1 ./instack-prepare-discovery

Places discovery.{kernel,ramdisk} and pxelinux.cfg/default into $TFTP_ROOT
Try to get Ironic URL from keystone for discovery configuration
Merge pull request #20 from Divius/setup-discovery-env

Add scripts/instack-prepare-discovery
Add patch for overcloud w/o merge.py to tripleo-heat-templates
Update heat templates merge.py patch
Run instack-prepare-for-overcloud as part of os-refresh-config
Install ironic, nova, and python-ironicclient from source and pull in needed ironic patch for discovery
allow this to fail gracefully since we are now always installing ironic from source
Add call to instack-prepare-discovery
Just don't do any of this since we're installing ironic from source
Must run as the stack user
Move key generate to install script so it runs as the stack user
Fix discovery image names
Use ironic builds from koji
Default NEUTRON_NETWORK_TYPE
Set up tripleo-heat-templates for Tuskar
Update patches for tuskar-ui and tuskar
Add tuskar element to installs
Add 2 patches for tuskar_ui
Use an environment.d to override TUSKAR_ROLE_DIRECTORY