Set heights to be equal

Set heights to be equal in admin panel for slider items. If a slider
items title is long enough it can break the styling of the admin page,
this commit should fix it.
Merge branch 'master' of https://github.com/AJSturrock/PyroCMS-Slider-Module
Set equal heights

Sets image slider items heights to be equal.
Merge pull request #3 from AJSturrock/master

Equal Heights