Fix issue with placedholder + IE8 + TEC

Place placehoder js in a seperate file
enqueue placholder script with a check if The Event Calendar has been
enqueued
Chnage Placeholder js to what we had before
Increase responsive script version
Add "min" to minified file names
Merge pull request #4 from cyberchimps/placeholder-script

Fix issue with placeholder + IE8 + The Event Calendar