Declare crypto as a dependency in pooler.app, don't start it

Let OTP do its thing.

src/pooler.app.src

@@ -5,7 +5,8 @@
   {registered, []},
   {applications, [
                   kernel,
-                  stdlib
+                  stdlib,
+                  crypto
                  ]},
   {mod, { pooler_app, []}},
   {env, []}

src/pooler_app.erl

@@ -10,7 +10,6 @@
 %% ===================================================================
 
 start(_StartType, _StartArgs) ->
-    application:start(crypto),
     case pooler_sup:start_link() of
         {ok, Pid} -> {ok, Pid};
         Other -> {error, Other}