Added Right-To-Left text direction support.

[johnallers]

When the HTML attribute dir="rtl" is set on the page, the input value does not get aligned properly with the knob. Use jquery.knob({ rtl: true }) to adjust the alignment appropriately.
Fixes #205

[meirotstein]

Hello, I was wondering why your change was not merged - I've tested it and it seems to solve this issue

[irandoct]

Hi,
the problem with RTL language exists yet. I tried the following but the value shows outside1
$(".dial").knob({
width : 300,
fgColor: "red",
font: "iranyekan",
rtl: true
});

Any Idea?