Style Improvements

I have tried to make some improvements to the UI.

* Improve spacing between elements. There was too much whitespace going on.
* Better placement of repeatable delete button
* Slightly different style for repeatable groups.
* Better file & image upload. 
	* Make it look more native - style taken from media upload modal.
	* Rethink of the label and button text to make things clearer.
	* Insert the image thumbnail for images, not the icon. 
	* Only display file name for files not images
	* Make it look nice - consistent style with image upload. Display repeatable inline. etc