Install diskimage-builder using packages
Set tripleo-heat-templates to specific git hash
Fix typo on bin/install.sh
Pass NovaComputeLibvirtType to Heat correctly
Switch back to using diskimage-builder from git

Also adds cherry picks for important fixes
Other changes needed for git diskimage-builder
Add another necessary cherry-pick for d-i-b
Merge branch 'master' into slagle/package
Merge branch 'master' into slagle/package
Merge from master