barcode pull request

Hi, I used the barcode code in our website because we were having problem with code39 and needed to use code128. We also needed text under the barcode so I added text to under the barcode when humanreadable is set to true.

We also had a different implementation in our code. so I added a function for display, very similar to base64, but separation of the content-type and the img uses src instead of data.

please let me know if you have any question, and thank you for the code.