Fixing foreach warning from undefined variable

[MichaelPereiraUK]

There is currently a 'Warning: Invalid argument supplied for foreach()' on 404 pages as the variable has never been defined, and doesn't get defined if it's a 404 page.

[grappler]

Thank you very much for the PR. The problem with this change is that there is a line where it is checking if the variable is set so that if the function is called multiple times it only runs once and the result is available in the variable.

I just committed a fix with a few other small improvements. https://github.com/flowplayer/wordpress-flowplayer/commit/05ca12e7336bca17647ab76bc4084ae780d45b02