Add some version checks to setup script

There are some distros out there, shipping quite outdated packages with
them, which results in weird issues. Let's check that we have a more or
less up to date version of node and yarn installed.

This patch adds those checks and this way should provide some helpful
error messages to people who try to install CodiMD.

Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>

bin/setup

@@ -2,6 +2,8 @@
 
 set -e
 
+version_lt() { test "$(printf '%s\n' "$@" | { [ "$(uname)" = "Linux" ] && sort -V || sort -t. -k 1,1n -k 2,2n -k 3,3n -k 4,4n; } | tail -n 1)" != "$1"; }
+
 # run command at repo root
 CURRENT_PATH=$PWD
 if [ -d .git ]; then
@@ -16,7 +18,23 @@ Read more on Node.js official website: https://nodejs.org
 And for yarn package manager at: https://yarnpkg.com/en/
 Setup will not be run
 EOF
-  exit 0
+  exit 1
+fi
+
+if version_lt "$(yarn --version)" '1.3.2'; then
+  cat <<EOF
+Your yarn version is outdated. Please upgrade to a version
+newer than 1.3.2.
+EOF
+  exit 1
+fi
+
+if version_lt "$(node --version)" 'v6.0.0'; then
+  cat <<EOF
+Your node version is outdated. Please upgrade to version 6
+or higher. (Version 8 or higher is recommended)
+EOF
+  exit 1
 fi
 
 echo "copy config files"