Add google eslint rules as a base

Remove some we don't care about. Set some other ones we do care
about but don't currently adhere to to warn. Set the max warnings
threshold to the current number of warnings, so we don't introduce
more of them. Fix a bunch of legit lint errors and add exceptions
to various places in the test code that does funny things with
'this'.

src/utils.js

@@ -348,16 +348,12 @@ var deepCompare = module.exports.deepCompare = function(x, y) {
  */
 module.exports.extend = function() {
     var target = arguments[0] || {};
-    // disable jshint "The body of a for in should be wrapped in an if
-    // statement"
-    /* jshint -W089 */
     for (var i = 1; i < arguments.length; i++) {
         var source = arguments[i];
-        for (var propName in source) {
+        for (var propName in source) { // eslint-disable-line guard-for-in
             target[propName] = source[propName];
         }
     }
-    /* jshint +W089 */
     return target;
 };