Add debian support for installing languages

Languages are installed at /usr/share/freeswitch/lang so that they can
be referred to by the user's configuration in /etc/freeswitch.  As a
Debian package user isn't going to have access to `make vm-sync` these
files need to be readily available somewhere.

debian/.gitignore

@@ -8,6 +8,7 @@
 /freeswitch-autotools.install
 /freeswitch-mod-*.install
 /freeswitch-conf-*.install
+/freeswitch-lang-*.install
 /freeswitch-music-*.install
 /freeswitch-sounds-*.install
 /*.lintian-overrides