Fix user namespace support

fix #153

For now, just create the default remap user, rather than trying
to fix the command emulation. The existing code in docker is not
ideal, as it is GNU specific, try to find a better option for
1.13.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

alpine/Dockerfile

@@ -64,8 +64,6 @@ COPY packages/hvtools/hv_set_ifconfig /sbin/
 COPY packages/hvtools/hvtools.tar.gz /usr/share/src/
 COPY packages/chronyd/etc /etc/
 COPY packages/userns/etc /etc/
-COPY packages/userns/groupadd /usr/sbin
-COPY packages/userns/useradd /usr/sbin
 #COPY packages/nc-vsock/nc-vsock /usr/bin
 COPY packages/vsudd/vsudd /sbin
 COPY packages/vsudd/etc /etc
@@ -117,4 +115,6 @@ RUN \
 
 COPY init /
 
+RUN adduser -D -H -s /sbin/nologin dockremap
+
 CMD ["/bin/sh"]

alpine/packages/userns/groupadd

@@ -1,3 +0,0 @@
-#!/bin/sh
-
-exec /usr/sbin/addgroup $@

alpine/packages/userns/useradd

@@ -1,13 +0,0 @@
-#!/bin/sh
-
-for a in $*
-do
-        [ "$a" = "-N" ] && a=""
-        [ "$a" = "-M" ] && a="-H"
-        [ "$a" = "-g" ] && a="-G"
-        args="$args $a"
-done
-
-echo $args
-
-exec /usr/sbin/adduser -D ${args}