Adds basic machine placement function for export.
Support lxcs in machine placement.
Merge pull request #553 from jaycee/update-export-to-include-machines

Support machine placement in bundle export

* Service placement on machines is based on unit placement, per deployer requirements.
* LXC, though partially implemented, is not officially supported because deployer support is spotty.
Tweak service nav tab's background.

Set the background to something that blends with the canvas, but won't
allow canvas elements (relations lines, services, etc.) to bleed
through.
Merge pull request #559 from kadams54/tab-fix

Tweak service nav tab's background.

Set the background to something that blends with the canvas, but won't
allow canvas elements (relations lines, services, etc.) to bleed
through.