fixed custom decimal point and float bug

Here's my attempt to describe the issue that have been fixed in this pull-request:

I have a page with two input fields. The fields are bootstrapped with jquery.number like this:

    $('.currency-format').number( true, 2 , ',', '.' );
    $('.currency-format-us').number( true, 2 );

To explain in words what I'm trying to do:

The first field "currency-format" needs to format numbers using "." (punctuation) as a thousand separator and "," (comma) as the decimal point character.

The second field "currency-format-us" needs to format numbers using a default us-currency format - meaning "," (comma) as the thousand separator and "." (punctuation) as the decimal point character.

**Expected result:**

First field: 1.234,99
Second field: 1,234.99

**Actual result:**

First field: 123.499,00 **<- incorrect!**
Second field: 1,234.99 <- correct!

The $.number method was accepting a float as the first parameter, meaning that an input of 123,99 in the "currency-format"-field would always be formatted as "123.99" rendering my custom decimal point and thousand separators irrelevant.

I've made a minor fix which will make sure that the decimal point separator is initially replaced with a custom one.

---

I hope this made sense. Not the easiest issue to explain. I tried to make a jsfiddle demo, but was unable to include this particular version of the plugin in the example. Although it's not a working example, I have saved it anyway. The only thing needed to demonstrate the issue is to include the missing jquery.number plugin in this particular version.

[Incomplete JSFiddle example](http://jsfiddle.net/jPPSW/)

Best regards
Brian