Add single method getters/setters

[ccampbell]

For example right now there are methods for App::getBasePath() and App::setBasePath() there can be a single method App::basePath() that either sets or gets depending on the variables passed to it.

For example this would return the base path::

$app = App::getInstance();
echo $app->basePath();

And this would set it:

$app = App::getInstance();
$app->basePath('/path/to/application');

This is already happening in certain places, but I think it should happen everywhere it is applicable.