Add helper script get_all_ifaces_for_host

Returns an array of all ifaces of a
particular host matching a type.

get_all_ifaces_for_host

@@ -0,0 +1,22 @@
+[%
+  # Returns the interface name with a certain type for a given host
+  #
+  # @param argv.host	The hostname to get the interface from.
+  # @param argv.type	The interface type
+  #			One of: web_int, web_ext, sip_int, sip_ext, ...
+  # @return out		The interface name
+-%]
+[% IF !hosts.${argv.host}.defined -%]
+[% argv.host = 'self' -%]
+[% END -%]
+[% out = [] -%]
+[% FOREACH iface IN hosts.${argv.host}.interfaces -%]
+[% FOREACH realiface IN hosts.${argv.host}.keys -%]
+[% IF realiface == iface -%]
+[% IF hosts.${argv.host}.$realiface.type.grep('^' _ argv.type _ '$').size() -%]
+[% out.push(realiface) -%]
+[% END -%]
+[% END -%]
+[% END -%]
+[% END -%]
+