bhyve validation tool

The goal of BVT is to provide a semi-automated framework for finding regressions in bhyve

It is a way to validate MFCd changes from HEAD to 10-stable.

1. Boot a series of pre-created virtual machine images
2. Each of these images is configured to do a number of tasks (start a web server that serves a file, run some basic tests of memory, cpu, and disk)
3. After a reasonable wait period, bvt checks to see if these tasks were completed
4. Calculate the results, all tests should pass (maybe we need a test that always fails to validate the results?)

1. Find breakages, 'changeset rXXXXXX breaks booting CentOS 6.5 under bhyve', 'changeset rXXXXXX segfaults when you try to write to the disk'
2. Speed up the process of validating changes to HEAD so they can be merged to 10-STABLE sooner