Request install support for cygwin

[drew-512]

Hi Gliders! First off, many thanks for a lovely package manager for Go and making life WAY easier. Hats off!

Kind request for Cygwin!

$ curl https://glide.sh/get | sh
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  4833  100  4833    0     0  22068      0 --:--:-- --:--:-- --:--:-- 21968
ARCH=amd64
OS=cygwin_nt-10.0
Using curl as download tool
Getting https://glide.sh/version
TAG=v0.13.2
GLIDE_DIST=glide-v0.13.2-cygwin_nt-10.0-amd64.tar.gz
Downloading https://github.com/Masterminds/glide/releases/download/v0.13.2/glide-v0.13.2-cygwin_nt-10.0-amd64.tar.gz
Did not find a release for your system: cygwin_nt-10.0 amd64
Trying to find a release on the github api.
LATEST_RELEASE_URL=https://api.github.com/repos/Masterminds/glide/releases/tags/v0.13.2
Getting https://api.github.com/repos/Masterminds/glide/releases/tags/v0.13.2
Sorry, we dont have a dist for your system: cygwin_nt-10.0 amd64