Updated input validity check

[arcreative]

Fixes billysbilling/billy-webapp#342
Fixes #1
Fixes #2

[arcreative]

@sebastianseilund Need your thoughts on an alternative to this solution.

We can't use unformat() to check validity because it's a bit of a doofus about the way that it handles non-numeric values. I actually raised a stink about this at https://github.com/adamwdraper/Numeral-js/ because there's no way to actually check a number's validity. If you do numeral().unformat('whale horse, haha'), it happily returns 0 which is.....not at all true. I've searched high and low, and none of the proposed solutions work with thousands delimiters.

I think the best solution would be to do a removal of the current locale's thousands delimiter, then return $.isNumeric(value); or something similar. Can't seem to find the current language's delimiter, however...

[arcreative]

For reference, here was my issue: adamwdraper/Numeral-js#53

[arcreative]

Ok, updated. My solution was to load numeral-languages, then pull the delimiters and use a regex to parse them out. Once the thousand delimiters are removed and the decimal delimiters are replaced with '.', the internal function should be good enough to determine whether or not it's valid.

[sebastianseilund]

I haven't checked out the code yet, but isn't value a string here, and therefore !isNaN(value) will always return true (because a string is not NaN)?

[arcreative]

No, it will take the string and cast it as a number first. For instance, !isNaN('2.5') === true.

[sebastianseilund]

Alright, let's get this one in then!