fcserver: Listen on localhost by default

This is more secure by default, and it allows fcserver to work correctly on Mac OS when no networking is available. (With wifi disabled, a server bound to 'null' won't be listening on localhost. Blah.)

examples/config-default.json

 {
-    "listen": [null, 7890],
+    "listen": ["127.0.0.1", 7890],
     "verbose": true,
 
     "color": {

examples/config-basic.json → examples/config-multi.json

 {
-    "listen": ["127.0.0.1", 7890],
+    "listen": [null, 7890],
     "verbose": true,
 
     "color": {

examples/config-networked.json

+{
+    "listen": [null, 7890],
+    "verbose": true,
+
+    "color": {
+        "gamma": 2.5,
+        "whitepoint": [1.0, 1.0, 1.0]
+    },
+
+    "devices": [
+        {
+            "type": "fadecandy",
+            "map": [
+                [ 0, 0, 0, 512 ]
+            ]
+        }
+    ]
+}

server/.gitignore

 *.o
 *.d
 fcserver
-
+fcserver-osx

server/main.cpp

@@ -31,7 +31,7 @@
 
 const char *defaultConfig =
     "    {\n"
-    "        \"listen\": [null, 7890],\n"
+    "        \"listen\": [\"127.0.0.1\", 7890],\n"
     "        \"verbose\": true,\n"
     "    \n"
     "        \"color\": {\n"