deployment: use 50% of RAM size for swap

The '5%-10G' sadly doesn't work as expected and 5% of the
*disk* size is a bad default, so let's see whether XX% of
RAM size makes a better choice. We might change the actual
percentage value but we need some testing anyway....

From: Michael Prokop <mprokop@sipwise.com>

deployment.sh

@@ -770,7 +770,7 @@ primary -       4096-   -       -
 disk_config lvm
 vg ngcp       ${DISK}1
 ngcp-root     /       95%       ext3 rw
-ngcp-swap     swap     5%       swap sw
+ngcp-swap     swap    RAM:50%   swap sw
 EOF
 
   # make sure setup-storage doesn't fail if LVM is already present