add test to verify all ext files are at least parseable

test/smoke-require-ext.js

@@ -0,0 +1,16 @@
+var fs = require('fs');
+var assert = require('assert');
+
+describe('all extension modules', function() {
+  it('should not throw when require\'d', function(done) {
+    var extFolder = __dirname + '/../lib/ext';
+    fs.readdir(extFolder, function(err, list) {
+      assert.ifError(err);
+      list.forEach(function(name) {
+        var m = require(extFolder + '/' + name);
+      });
+      done();
+    });
+  }
+})
+