Fix wildcard TLS domain detection

As per RFC 2818 [0], a CN of *.dokku.me will only match direct
subdomains of dokku.me, not sub-subdomains like www.test.dokku.me, but
Dokku currently enables TLS for subdomains of all levels.

I have changed the regex from .*\.dokku\.me to [^.]*\.dokku\.me so TLS
is only enabled for direct subdomains.

[0] - http://tools.ietf.org/html/rfc2818#section-3.1

Signed-off-by: Lewis Marshall <lewis@lmars.net>

tests/unit/nginx-vhosts.bats

@@ -65,9 +65,11 @@ assert_http_success() {
   setup_test_tls_wildcard
   add_domain "wildcard1.dokku.me"
   add_domain "wildcard2.dokku.me"
+  add_domain "www.test.dokku.me"
   deploy_app
   assert_ssl_domain "wildcard1.dokku.me"
   assert_ssl_domain "wildcard2.dokku.me"
+  assert_nonssl_domain "www.test.dokku.me"
 }
 
 @test "nginx:build-config (with SSL CN mismatch)" {