Repaired task reordering issue

* Created `conditionalOrderBy` filter with a similar signature to `orderBy`,
  using a single conditional argument that when false, causes the filter to
  return the array unchanged

* Updated task view to use `conditionalOrderBy`

* Added karma specs for `conditionalOrderBy` filter

test/spec/filtersSpec.js

@@ -0,0 +1,30 @@
+'use strict';
+
+describe('Custom Filters', function() {
+  var filter
+    , orderBySpy = sinon.spy();
+
+  beforeEach(function() {
+    module(function($provide) {
+      $provide.value('orderByFilter', orderBySpy);
+    });
+    inject(function($rootScope, $filter) {
+      filter  = $filter;
+    });
+  });
+
+  describe('conditionalOrderBy', function() {
+    describe('when the predicate is true', function() {
+      it('delegates the arguments to the orderBy filter', function() {
+        filter('conditionalOrderBy')('array', true, 'sortPredicate', 'reverseOrder');
+        expect(orderBySpy).to.have.been.calledWith('array','sortPredicate','reverseOrder');
+      });
+    });
+
+    describe('when the predicate is false', function() {
+      it('returns the initial array', function() {
+        expect(filter('conditionalOrderBy')([1,2,3], false)).to.eql([1,2,3]);
+      });
+    });
+  });
+});