Code style / syntax cleanup #1

These are code style and minor syntax changes. So nothing in functionality should be changed.

This PR is the first in a series (to come).

This is a cleanup of the following folders:

/administrator/components/com_admin
/administrator/components/com_banners
/administrator/components/com_cache

administrator/templates/hathor/html/com_admin
administrator/templates/hathor/html/com_banners
/administrator/templates/hathor/html/com_cache

#### Testing instructions
Check if all the views of these components still function as expected.