Two little PTG portlet improvements

Hello !

"add portlet methods to return all images"
- default portlet shows only 1 image at once...
- sometimes we need more, i.e. my PTG portlet custom (template override) displays 12 thumbnails at once
- no impact on the existing portlet behavior

"fix character encoding in portlet image titles"
- the portlet did not support french accents well
- flickr uses utf8 charset so I added utf8 encoding on the title

Thank you again for this great product :)