Load balance the site across supported backends

[amirmc]

From the MirageOS mailing list

To do this we would need to:

• modify the Travis deployment scripts to build all the variants and not just Xen/x86_64
• alter mirage-www to include information on which backend it is using and display it in the HTML
• deploy a couple of DNS unikernels that do RR balancing across each of the different backends.

See email at: http://lists.xenproject.org/archives/html/mirageos-devel/2015-05/msg00014.html

[yomimono]

These are still good ideas, especially now that we have even more backends! This might be a good project for the hack retreat - @avsm, do we have resources available for that?