Add main/1 so rebar2 escriptize works

Change-Id: Ifc3a58d09fbf5b9f36595515f47223a45ef13ba1

rebar.config

@@ -29,3 +29,7 @@
 	{plt_extra_apps, [kernel, stdlib, erts, tools, inets, compiler, diameter]},
 	{warnings, [no_improper_lists]}
 	]}.
+
+{escript_incl_apps, [osmo_dia2gsup]}.
+{escript_main_app, osmo_dia2gsup}.
+{escript_name, "osmo-dia2gsup"}.

src/osmo_dia2gsup.erl

@@ -5,6 +5,8 @@
 -include_lib("diameter/include/diameter_gen_base_rfc6733.hrl").
 %-include_lib("diameter_settings.hrl").
 
+-export([main/1]).
+
 % API
 -export([start_link/0]).
 -export([start/0, stop/0]).
@@ -54,6 +56,10 @@ start() ->
 stop() ->
 	gen_server:cast(?SERVER, stop).
 
+main(_Args) ->
+	application:ensure_all_started(?MODULE),
+	timer:sleep(infinity).
+
 %% ------------------------------------------------------------------
 %% gen_server Function Definitions
 %% ------------------------------------------------------------------