Use global installations of dependencies

Projects where handlebars, underscore and json2 are dependencies of
modules others than require-handlebars may prefer using their existing
libraries installation and require.js paths setup.

The current patch uses common global module IDs for these dependencies,
instead of relying on the shipped ones.

hbs.js

@@ -11,7 +11,7 @@
 define: false, process: false, window: false */
 define([
 //>>excludeStart('excludeHbs', pragmas.excludeHbs)
-  'hbs/handlebars', 'hbs/underscore', 'hbs/i18nprecompile', 'hbs/json2'
+  'handlebars', 'underscore', 'hbs/i18nprecompile', 'json2'
 //>>excludeEnd('excludeHbs')
 ], function (
 //>>excludeStart('excludeHbs', pragmas.excludeHbs)
@@ -89,7 +89,7 @@ define([
     };
 
     fetchText = function (url, callback) {
-      var xdm = false;  
+      var xdm = false;
       // If url is a fully qualified URL, it might be a cross domain request. Check for that.
 	  // IF url is a relative url, it cannot be cross domain.
       if (url.indexOf('http') != 0 ){
@@ -101,7 +101,7 @@ define([
           var msie = getIEVersion();
               xdm = ( dom != window.location.href.substr(hidx).split('/').shift() ) && (msie >= 7);
       }
-      
+
       if ( xdm ) {
          var xdr = getXhr(true);
         xdr.open('GET', url);
@@ -418,7 +418,7 @@ define([
               var path;
               if(partialReference.match(/^(\.|\/)+/)) {
                 // relative path
-                path = cleanPath(baseDir + partialReference) 
+                path = cleanPath(baseDir + partialReference)
               }
               else {
                 // absolute path relative to config.hbs.partialsUrl if defined
@@ -524,12 +524,12 @@ define([
 
           if(depStr) depStr = ", '"+depStr+"'";
 
-          var partialReferences = []; 
+          var partialReferences = [];
           if(require.config.hbs._partials[name])
-            partialReferences = require.config.hbs._partials[name].references; 
+            partialReferences = require.config.hbs._partials[name].references;
 
           text = '/* START_TEMPLATE */\n' +
-                 'define('+tmplName+"['hbs','hbs/handlebars'"+depStr+helpDepStr+'], function( hbs, Handlebars ){ \n' +
+                 'define('+tmplName+"['hbs','handlebars'"+depStr+helpDepStr+'], function( hbs, Handlebars ){ \n' +
                    'var t = Handlebars.template(' + prec + ');\n';
 
           for(var i=0; i<partialReferences.length;i++)