Update styling for <label> tag in the dialog

Problem/Motivation

The ckeditor_templates dialog needs some styling tweaks. If template icons are grey or have any transparency to them, it becomes really hard to see the icons. Additionally, I suggest the template name should be vertical aligned middle, so they are better aligned with the icon on the left.

Proposed resolution

• Remove grey background on label:hover
• Set vertical alignment of template name inside the label