Added CSV quotation for delimiters

[vratiu]

I've encountered some issues when trying to convert files that had commas, CRLF or double quotes in filed.
I followed directions in http:https://tools.ietf.org/html/rfc4180 "2. Definition of the CSV Format" and enclosed the value with double quotes if it containes delimiters or double quotes

[coveralls]

Coverage remained the same when pulling 349af44 on vratiu:improved_csv_quote into 0cfb22e on SheetJS:master.

[SheetJSDev]

@vratiu Thanks :)

A few changes (and if you can squash/amend, that would be great):

1. opts = opts || {}; appears to have the wrong indentation (you added another level?)

2. Add the line "Fixes #32" at the bottom of the commit message (I think your patch would also resolve added case for german languaged Worksheets sheetjs#32)

[SheetJSDev]

@vratiu I should add the notes to this repo, but please look over https://github.com/SheetJS/js-xlsx/blob/master/CONTRIBUTING.md and make sure everything looks good.

[vratiu]

@SheetJSDev I've updated the code. I hope all looks well.
Everything looks good on the contributors side.

[SheetJSDev]

Can you squash the two commits into one? (make it one commit). Then I can merge :)

[SheetJSDev]

@vratiu Perfect! Thank you very much

[vratiu]

No problem. Thanks for creating the library :-)