Fixed nullPointerException on failed upload
Updated user agent and token

@JayFoxRox is a legend, I can't give him enough credit for the last few
days that he put into this!
Update README.md
Merge branch 'master' of https://github.com/shirioko/WhatsAPI
Fixed a lot of CSS issues. Now works much better when viewed on mobile device.
Included the required "chosen" module to fix selection of numbers to send message to. Apologies!