Added the steps to download the playerglobal.swc to the setup.sh script
Added some general bullet-proofing to the setup.sh script
Removed the playerglobal.swc download steps from the README.md

Testing:
tested setup.sh with no arguments - printed usage information
tested setup.sh with valid video_js_dir and flex_sdk_dir - script completed successfully
tested setup.sh with only a valid video_js_dir - script complained that it couldn't find the flex_sdk_dir
tested setup.sh with only a valid flex_sdk_dir - script complained that it couldn't find video.js at flex_sdk_dir
tested setup.sh with only a invalid video_js_dir and valid flex_sdk_dir - script complained that it couldn't find video.js the video_js_dir
tested setup.sh with valid video_js_dir and flex_sdk_dir - script completed successfully
Added download of playerglobal.swc to setup.sh
Added some bulletproofing to setup.sh
Removed download steps from README.md

Fixed some merge conflicts with setup.sh