Only use mouse event click

Hey,

Finally got around to addressing your comment over at: https://github.com/borismus/keysocket/pull/31#commitcomment-4556456

Sorry about the delay have been tied down with college work.

I have removed the click down click up code. Not sure why it was there in the first place. I based the simulateClick function of pre-existing code within the extension.

Testing with just using the click mouse event seems to work just fine.