Fixes for id attar + add click attr for callback.

First of all - with the latest version of jqplot this directive is not working for me, because it call $(element).jqplot, but according to official jqplot's documentation there is only one appropriate way - $.jqplot('elemente's id' ....);
Second - I have added chart-click attribute to pass a function that will be called when event 'jqplotDataClick' is fired.