Guard against the pitfalls found in Darren's setup

[msprotz]

• Definitely discourage the use of Git for Windows; the two-factor auth prompt just blocks the process
• Check that it's not a mixed up cygwin32/cygwin64 installation
• Check that there's no /usr/bin/flexdll (because of the point above)
• Make sure we also install curl
• Check that HOME is of the form drive:/cygwin64/home/foo
• Check that there's a ~/.bash_profile

[msprotz]

Also should suggest the tip at the end of https://github.com/protz/ocaml-installer/wiki for /etc/nsswitch.conf that everyone on the corporate microsoft network seems to have