Export Frisby constructor to support plugins (#29)

Support a mixin pattern inspired by http://justinfagnani.com/2015/12/21/real-mixins-with-javascript-classes/

lib/icedfrisby.js

@@ -43,27 +43,6 @@ let _init = _icedfrisbyDefaults();
 let _initDefined = false;
 
 
-/**
- * specify global defaults for IcedFrisby test run
- * @param {object} obj - setup object
- * @return {object}
- * @desc global setup function
- */
-function globalSetup(obj) {
-  if (!_.isUndefined(obj)) {
-    if (_initDefined) { globalSetupDefined(_init, obj); }
-
-    _initDefined = true;
-    _init = _.merge(_.cloneDeep(_icedfrisbyDefaults()), obj);
-
-    if(_init.useApp) {
-      _init.request.baseUri = _useAppImpl(_init.useApp);
-    }
-  }
-  return _init;
-}
-
-
 /**
  * warn or die if user uses globalSetup() improperly
  * @param {object} init -
@@ -103,6 +82,8 @@ function _hasHeader(headername, headers) {
 
 
 /**
+ * Parse body as JSON, ensuring not to re-parse when body is already an object
+ * (thanks @dcaylor).
  * @param {object} body - json object
  * @return {object}
  * @desc parse response body as json
@@ -149,7 +130,7 @@ function _useAppImpl (app, basePath) {
  * @desc create IcedFrisby object
  */
 function Frisby(msg) {
-  let clone = _.cloneDeep(globalSetup());
+  let clone = _.cloneDeep(Frisby.globalSetup());
 
   if(clone.request && clone.request.headers) {
     let headers = {};
@@ -195,6 +176,39 @@ function Frisby(msg) {
 
   return this;
 }
+module.exports = Frisby;
+
+
+Frisby.version = pkg.version;
+
+
+/**
+ * specify global defaults for IcedFrisby test run
+ * @param {object} obj - setup object
+ * @return {object}
+ * @desc global setup function
+ */
+Frisby.globalSetup = function (obj) {
+  if (!_.isUndefined(obj)) {
+    if (_initDefined) { globalSetupDefined(_init, obj); }
+
+    _initDefined = true;
+    _init = _.merge(_.cloneDeep(_icedfrisbyDefaults()), obj);
+
+    if(_init.useApp) {
+      _init.request.baseUri = _useAppImpl(_init.useApp);
+    }
+  }
+  return _init;
+};
+
+
+/**
+ * Main Frisby method used to start new spec tests
+ */
+Frisby.create = function (msg) {
+  return new Frisby(msg);
+};
 
 
 /**
@@ -1228,22 +1242,3 @@ Frisby.prototype.toss = function (retry) {
 
   });
 };
-
-//
-// Parse body as JSON, ensuring not to re-parse when body is already an object (thanks @dcaylor)
-//
-
-////////////////////
-// Module Exports //
-////////////////////
-
-//
-// Main Frisby method used to start new spec tests
-//
-exports.create = function(msg) {
-  return new Frisby(msg);
-};
-
-// Public methods and properties
-exports.globalSetup = globalSetup;
-exports.version = pkg.version;