Image format default should be the first of the declared format when seeding

[heimdallr]

I have declared a properties file with the only mime type as image/gif. When attemtping to seed the cache,

http://hqsuvalhalla:8080/geowebcache/seed?layers=admin1_epsg900913&start=4&stop=12

throws a error stating that PNG is not supported.

http://hqsuvalhalla:8080/geowebcache/seed?layers=admin1_epsg900913&start=4&stop=12&format=image/gif

seems to work fine.

[arneke]

Fixed in r54, thanks