Merge pull request #271 from facine/master

Fix properties typo. && Add auto-upload images to WhatsApp servers and auto-generate icon.
Merge pull request #272 from facine/master

Add support for auto-upload audio/video and send it, support for send vCars and more!
Merge pull request #275 from facine/master

Event callback implementation.
Update README.md
Update README.md