Use help2man to generate man pages (fixes #165)

A little more lightweight than the doxygen approach,
and keeps the documentation harmonized with --help.

h/t to A. Maitland Bottoms for pointing me to this.
libbladeRF: Corrected documentation commands in README.md
Merge branch 'dev-issue165-use-help2man-rev3' from https://github.com/rtucker/bladeRF
host: Added option to disable "warnings as errors" in builds

Developers should always build with -Werror or /WX. However, we've had a
few cases with different compiler versions throwing errors that devs
didn't see, breaking master for users. The intention of this change is
to give those users a quick workaround, rather than requiring them to
hack around the warning in the source.
host: Updated README.md to include CMake TREAT_WARNINGS_AS_ERRORS option