Make auto-scroll behavior optional

_(first off, thanks very much for the excellent library. it's the bee's knees)_

As mentioned in #50, the auto-scroll behavior is particularly irksome if you have multiple consoles on one page.

This patch introduces a new (optional) parameter to the `jqconsole` constructor (& jquery function) that turns off auto-scroll.

If the argument is omitted, default behavior remains the same as before.

Cheers!

[EDIT: removed compiled & minified files, fixed camel-case variable that should be underscore'd]

~~[EDIT2: actually, this breaks auto-scrolling the `<pre>` element as well. Fix will be coming soon.]~~
If we just check for truthiness, then the argument will be required. If the argument is left out, auto-scroll behavior will be turned off, whereas now auto-scroll is turned on by default.

I'm fine with changing it if that's what you want - just want to clarify.