Allow completely offline bootstrap.
switch to ssh url for development
Merge remote-tracking branch 'origin/offline'
use public url
remove optimization

it wouldn't download the iso initially, otherwise
pin ansible to < 1.6 until we fix bsdploy to work with it
leave out redundant parameter
todos
fixup for 1e498838d9abe01c39c18fef5942a9b503895148
adjust to https://github.com/tomster/bsdploy/commit/3572bd3aac928e2ac04923aca0c7feff5257654a
add explicit development requirements and install them
fixup for 75fece36f9bfd5705dad4bc364f247953e6ca9bf
don't delete bin, it contains versioned files!
fetch assets beforehand

currently installing from remote assets is broken
don't prefetch assets by default

it is too fragile (i.e. needs brew install xz on osx and even then we had instances of it now working)
cosmetics
fixup to f143ddc12f3bd0bb1e114cba6e8d90bd130c3890
allow building with newer XCode
allow installing releases of bsdploy & friends

but still preserve ability to install development versions
remove debugging cruft