.deb/.rpm: add osmocom user during package install

Created osmocom user & group during package installation.
Fix the configuration dir/files permission to match.

Related: OS#4107
Tweaked-By: Oliver Smith <osmith@sysmocom.de>
Change-Id: I41d47c0884d09d4674ec806d77e43bc8f08d9b64
diff --git a/debian/control b/debian/control
index 64bb73c..00c1b26 100644
--- a/debian/control
+++ b/debian/control
@@ -31,7 +31,7 @@
 Package: osmo-msc
 Architecture: any
 Multi-Arch: foreign
-Depends: ${misc:Depends}, ${shlibs:Depends}
+Depends: ${misc:Depends}, ${shlibs:Depends}, adduser
 Recommends: osmo-mgw
 Description: OsmoMSC: Osmocom's Mobile Switching Center for 2G and 3G circuit-switched mobile networks
   The Mobile Switching Center (MSC) is the heart of 2G/3G