changed the /dev/image channel type to 3

the /dev/image default channel type was always 1 (append-only channel)
but with recent developments in zrt and future introduction of real append-only channels it should be moved to 3 (randomly readable)
Merge pull request #36 from pkit/config_fixes

changed the /dev/image channel type to 3
fixed bug inroduced in c567b10

swift:// url relative path feature was not tested enough
added proper tests and fixed bugs
Merge pull request #37 from pkit/proxy_fixes2

fixed bug inroduced in c567b10