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.]~~
just use `auto_scroll` without the `@` because this variable isn't used out of the constructor