Add a lightweight browser version of "depd"

The module "depd" does not support browser and it is not trivial
to fix that. This commits adds a lightweight implementation
of the depd "deprecate" function.

lib/browser.depd.js

@@ -0,0 +1,16 @@
+// A lightweight alternative to "depd" that works in the browser
+module.exports = function depd(namespace) {
+  var warned = {};
+  return function deprecate(message) {
+    if (warned[message]) return;
+    warned[message] = true;
+
+    if (process.noDeprecation) {
+      return;
+    } else if (process.traceDeprecation) {
+      console.trace(namespace, 'deprecated', message);
+    } else {
+      console.warn(namespace, 'deprecated', message);
+    }
+  };
+};

package.json

@@ -16,6 +16,9 @@
     "url": "https://github.com/strongloop/loopback-datasource-juggler"
   },
   "main": "index.js",
+  "browser": {
+    "depd": "./lib/browser.depd.js"
+  },
   "scripts": {
     "test": "make test"
   },