ZNC: switch from root user earlier, support --user

Fixes https://github.com/znc/znc-docker/issues/20 and
https://github.com/znc/znc-docker/issues/12

library/znc

@@ -1,6 +1,6 @@
 Maintainers: Alexey Sokolov <[email protected]> (@DarthGandalf)
 GitRepo: https://github.com/znc/znc-docker.git
-GitCommit: 207358a4830566913c1f9b6c0cdb870c5b6c7bb3
+GitCommit: 4da25330d7d4415507c5abd24efa74130243a5b3
 Architectures: amd64, arm32v6, arm64v8
 
 Tags: 1.7.2, 1.7, latest