Fix parsing of image properties

when more then one pair of key/value's are given
then this code shows wrong behavior:

vm_mode=exe,cinder_img_volume_type=vstorage
it makes this:
vm_mode=''exe',cinder_img_volume_type=vstorage'

Reason is the first conversion being to broad, and 2nd match matches
the whole string.

Change-Id: I5bcf23374b57197680b87b554392ee172bf90571

lib/puppet/type/glance_image.rb

@@ -89,9 +89,7 @@ Puppet::Type.newtype(:glance_image) do
     munge do |value|
       return value if value.is_a? Hash
 
-      # wrap property value in commas
-      value.gsub!(/=(\w+)/, '=\'\1\'')
-      Hash[value.scan(/(\S+)='([^']*)'/)]
+      Hash[value.scan(/([^,=]+)=([^,]*)/)]
     end
 
     validate do |value|