small issue in psnGallery2

Issue description: If the <cpg_xxxx> tag is used with only 1 parameter and no separator, nothing is displayed.
Discover by: William Spaetzel
Final Fix : next release (probably 1.3.0)
Workaround: use the tag with parameters (eg: <cpg_gallery>3|2|1</cpg_gallery> instead of <cpg_gallery>3</cpg_gallery>)