Refactor dependencies installation

install_dependencies.sh

-puppet module install puppetlabs-ruby
-puppet module install jgoettsch/mercurial
-puppet module install puppetlabs/apache
-puppet module install puppetlabs/postgresql
-puppet module install puppetlabs/rsync
-puppet module install maestrodev/wget
-puppet module install glarizza-pick
-puppet module install camptocamp-archive
-puppet module install puppetlabs-java
-puppet module install stahnma-epel
+#!/bin/bash
+
+MODULES_TO_INSTALL="puppetlabs-ruby jgoettsch-mercurial puppetlabs-postgresql puppetlabs-rsync maestrodev-wget camptocamp-archive puppetlabs-java stahnma-epel jfryman-nginx"
+MODULES_INSTALLED=`puppet module list`
+
+for i in ${MODULES_TO_INSTALL}; do
+  # only install module if needed
+  echo ${MODULES_INSTALLED} | grep -q $i || puppet module install $i
+done
+