Added GitHub markdown information to README

Merge pull request #11 from oshybystyi/support-for-github-flavoured-md

Added support for github flavoured markdown

Added support for github flavoured markdown

Made temp file and toggle global variables; updated README

Updated README to show defaults

Updated README to show image support; Added new screenshot

Include Safari on OSX

Don't remove temporary files, and removed the time delay

Changed mapping to Ctrl-p instead of write until bux is fixed.

Added screenshot

Added on write to buffer trigger

Added background tab refreshing.
Supported for *nix.
Close #1

Initial commit