modify currency regexes to handle decimal points

For original issue ticket see: #39 

I decided to leave out the zero omission, as I couldn't come up with any programming languages which would output floats as so. There was also a typo in comments on line 117, which I fixed. I also added all current currencies to the suffixed regex, even though only euros are actually typed so. We in Europe tend to many times forget that US dollars are prefixed with the sign.

Since there were no tests, I used http://regex101.com to come up with inputs of my own. So far, I haven't come up with any inputs which would result in bad data, although the third regex (on line 118) parses numbers such as 111.111.111 as valid. I don't really see a case where this would happen, but in case you see this as something you want sorted out, I could take a look at it. I don't just see it to affect this particular PR, so I'll let it untouched for now.

Also, `grunt` updated the version into `1.6.4`, but seemingly the `package.json` already has that, so I guess you know what is going on. That being said, the primary Github branch is also called `gh-pages`.