Fixes rvm installation

When provisioning the VM, the rvm installation was failing because gpg
can't check signature (public key not found).  This additional step
downloads the signature for the RVM package so the provisioning can
finish.

puppet/manifests/default.pp

@@ -63,6 +63,10 @@
 
 # --- Ruby ---------------------------------------------------------------------
 
+exec { 'install_gpg_keys':
+  command => "${as_vagrant} 'gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3'",
+}
+
 exec { 'install_rvm':
   command => "${as_vagrant} 'curl -L https://get.rvm.io | bash -s stable'",
   creates => "${home}/.rvm/bin/rvm",
@@ -81,7 +85,7 @@
 }
 
 # RVM installs a version of bundler, but for edge Rails we want the most recent one.
-exec { "install_bundler": 
+exec { "install_bundler":
   command => "${as_vagrant} 'gem install bundler --no-rdoc --no-ri'",
   creates => "${home}/.rvm/bin/bundle",
   require => Exec['install_ruby']
@@ -100,7 +104,7 @@
 
 stage { 'dc-housing': }
 
-class dc-housing-setup { 
+class dc-housing-setup {
   package { "pdftk":
     ensure => latest
   }