ionic-framework: bug: ng-click handlers called twice on IE

@jdnichollsc try to add type="button" to the button element. As @cverb pointed in this SO issue the default behaviour is submit and apparently that messes with the code. At least my issue was fixed.

I confirm that the bug append in IE11. Replacing <button> by <a class="button"> works but would be better to handle it in the lib.

My solution is to overwrite the ng-click handling and simply drop the second event:

ionic.Platform.isIE = function() {
  return ionic.Platform.ua.toLowerCase().indexOf('trident') > -1;
}

if (ionic.Platform.isIE()) {
  angular.module('ionic')
    .factory('$ionicNgClick', ['$parse', '$timeout', function($parse, $timeout) {
      return function(scope, element, clickExpr) {
        var clickHandler = angular.isFunction(clickExpr) ? clickExpr : $parse(clickExpr);

        element.on('click', function(event) {
          scope.$apply(function() {
            if (scope.clicktimer) return; // Second call
            clickHandler(scope, {$event: (event) });
            scope.clicktimer = $timeout(function() { delete scope.clicktimer; }, 1, false);
          });
        });

        // Hack for iOS Safari's benefit. It goes searching for onclick handlers and is liable to click
        // something else nearby.
        element.onclick = function(event) {};
      };
    }]);
}

The magic is around the clicktimer part.