Stack v1.5.0 Release Candidate

[Emanuel Borsboom]

I've built the stack-1.5.0 binaries, and some extra people trying them for a few days before we release them to the public would be great. You can get them here: https://github.com/commercialhaskell/stack/releases/tag/v1.5.0-rc1

In particular, we'd like help testing:

* The new Linux static binary, especially if you use a "less mainstream" Linux distro (e.g. not Ubuntu/Debian/RedHat/CentOS). The static build process has changed significantly so a sanity check on as many distros as possible would be great. Note that we're testing that Stack *itself* can run, not necessarily that `stack setup` fully supports installing GHC on the less common distributions (which is a separate issue). Get it here: https://github.com/commercialhaskell/stack/releases/download/v1.5.0-rc1/stack-1.5.0-linux-x86_64-static.tar.gz

* The new Windows binary/installer. We aren't heavy Windows users, and I had some trouble on my build VM that forced me to wipe out all my stack root and .stack-work directories, so some sanity checking by Windows users would be most helpful. Get the installer here: https://github.com/commercialhaskell/stack/releases/download/v1.5.0-rc1/stack-1.5.0-windows-x86_64-installer.exe

[Emanuel Borsboom]

I haven't heard any reports of trouble with the RC, so unless I hear otherwise soon I'll publish the final 1.5.0 today!