Install script fails if wget is not available

[erikwilson]

Even though we don't use wget we test for its existence, and which wget returns a non-zero exit code which causes the script to silently fail.

root@1ed0ad1de566:/# curl -sfL https://get.k3s.io | sh -
[INFO]  Creating uninstall script /usr/local/bin/k3s-uninstall.sh
[INFO]  Downloading https://github.com/rancher/k3s/releases/download/v0.1.0-rc8/sha256sum-amd64.txt
[INFO]  Downloading https://github.com/rancher/k3s/releases/download/v0.1.0-rc8/k3s
[INFO]  Verifying download
[INFO]  Installing k3s to /usr/local/bin/k3s
[INFO]  systemd: Creating /etc/systemd/system/k3s.service
[INFO]  systemd: Enabling k3s unit
[INFO]  systemd: Starting k3s
root@1ed0ad1de566:/# rm /bin/wget
root@1ed0ad1de566:/# curl -sfL https://get.k3s.io | sh -
[INFO]  Creating uninstall script /usr/local/bin/k3s-uninstall.sh
root@1ed0ad1de566:/#