Update dependency install script

Author: benhylau

install-dependencies.sh

@@ -1,20 +1,4 @@
 #!/usr/bin/env bash
 
-# Check for required tools
-echo "Checking for markdown-pdf node module"
-npm -g list markdown-pdf
-S=$?
-if [ $S -ne 0 ]; then
-    echo "markdown-pdf is missing, install by running:"
-    echo "    npm install -g markdown-pdf"
-    return $S
-fi
-
-echo "Checking for gitbook-cli node module"
-npm -g list gitbook-cli
-S=$?
-if [ $S -ne 0 ]; then
-    echo "gitbook-cli is missing, install by running:"
-    echo "    npm install -g gitbook-cli"
-    return $S
-fi
+npm install -g markdown-pdf
+npm install -g gitbook-cli