Fluid-5255: Add a grade into uiOptions component so the path to the toc template is configurable

The API documentation change is required when this pull request gets into the master branch.

The new API to specify the path to the toc template as an option:
            fluid.uiOptions.prefsEditor(".flc-prefsEditor-separatedPanel", {
                gradeNames: "fluid.uiOptions.distributeTocTemplate",
                tocTemplate: customizedTocTemplate
            });
Note the presence of the new grade "fluid.uiOptions.distributeTocTemplate" which is responsible for passing down the "tocTemplate" option to the right spot on the tree.

The issue ticket: http://issues.fluidproject.org/browse/FLUID-5255