At some point the Ironic iPXE configuration changed.
The params now passed are full URLs and it is no longer
necessary for us to write the beginning of the URL out.
Additionally update the ownership of the boot.ipxe file so
ironic is able to overwrite it. Far from ideal, but required
at this time.
Closes-Bug: #1490546
Closes-Bug: #1490557
Change-Id: I1a54ac6dce1497823795f896907663b44ebaa67d
0869e7b756