Making the code more secure

$start_timestamp and $end_timestamp have been updated
Trying to make $controller more secure

$controller needs to be more secure.. I am unaware what it is taking in,
so esc_html may be incorrect for it.
$m missed esc_attr
Still needs to be fixed up some more,  but it's a start.

Trying to make $category_id more secure. I assume $category_id is only
taking numbers, if we're taking pretty links as the id, then my approach
won't work.
added prepare to the queries

Added prepare to the queries.
Added in prepare

A comment noting this has been updated with prepare
Merge branch 'master' of https://github.com/planetzuda/WP-e-Commerce

Conflicts:
	wpsc-includes/misc.functions.php