added script for installing kpt

hack/install_kpt.sh

@@ -0,0 +1,76 @@
+#!/bin/bash
+
+# If no arguments are given -> Downloads the most recently released
+# kpt binary to your current working directory.
+# (e.g. 'install_kpt.sh')
+#
+# If one argument is given -> Downloads the specified version of the
+# kpt binary to your current working directory.
+# (e.g. 'install_kpt.sh 0.34.0')
+#
+# If two arguments are given -> Downloads the specified version of the
+# kpt binary to the specified directory.
+# (e.g. 'install_kpt.sh 0.34.0 $(go env GOPATH)/bin')
+#
+# Fails if the file already exists.
+
+if [ -z "$1" ]; then
+    version=""
+  else
+    version=$1
+fi
+
+if [ -z "$2" ]; then
+    where=$PWD
+  else
+    where=$2
+fi
+
+if [ -f $where/kpt ]; then
+  echo "A file named kpt already exists (remove it first)."
+  exit 1
+fi
+
+tmpDir=`mktemp -d`
+if [[ ! "$tmpDir" || ! -d "$tmpDir" ]]; then
+  echo "Could not create temp dir."
+  exit 1
+fi
+
+function cleanup {
+  rm -rf "$tmpDir"
+}
+
+trap cleanup EXIT
+
+pushd $tmpDir >& /dev/null
+
+opsys=windows
+if [[ "$OSTYPE" == linux* ]]; then
+  opsys=linux
+elif [[ "$OSTYPE" == darwin* ]]; then
+  opsys=darwin
+fi
+
+curl -s https://api.github.com/repos/GoogleContainerTools/kpt/releases |\
+  grep browser_download |\
+  grep $opsys |\
+  cut -d '"' -f 4 |\
+  grep /kpt/releases/download/v$version |\
+  sort | tail -n 1 |\
+  xargs curl -s -O -L
+
+if [ -e ./kpt_${opsys}_amd64-*.tar.gz ]; then
+    tar xzf ./kpt_${opsys}_amd64-*.tar.gz
+else
+    echo "Error: kpt binary with the version $version does not exist!"
+    exit 1
+fi
+
+cp ./kpt $where
+
+popd >& /dev/null
+
+$where/kpt version
+
+echo kpt installed to specified directory.