base-files: remove shebang from uci-defaults files

uci-defaults are sourced and non-executable, so they do not require
a shebang.

While at it, apply consistent naming scheme.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

package/base-files/files/etc/uci-defaults/10_migrate-shadow

@@ -1,5 +1,3 @@
-#!/bin/sh
-
 ppwd="$(sed -ne '/^root:/s/^root:\([^:]*\):.*$/\1/p' /etc/passwd)"
 spwd="$(sed -ne '/^root:/s/^root:\([^:]*\):.*$/\1/p' /etc/shadow)"
 

package/base-files/files/etc/uci-defaults/12_network-generate-ula

@@ -1,5 +1,3 @@
-#!/bin/sh
-
 [ "$(uci -q get network.globals.ula_prefix)" != "auto" ] && exit 0
 
 r1=$(dd if=/dev/urandom bs=1 count=1 |hexdump -e '1/1 "%02x"')

package/base-files/files/etc/uci-defaults/13_fix-group-user

@@ -1,5 +1,3 @@
-#!/bin/sh
-
 . /lib/functions.sh
 
 for file in `grep -sl Require-User /usr/lib/opkg/info/*.control`; do