only those who can manage_options should be allowed access

Unless I am mistakened, only those who can manage_options will need
access to this class and functions, so it doesn't hurt to disallow
access to the file if you can't manage_options.
locked down some files with current_user_can

locked down some files that only admins should need access to.
minor change reflect manage_options

Removed wp_kses from one of my commits, since I went with
manage_options, instead.
fixed a stupid mistake I made

Users should be able to access the dashboard. DOH!
fixing mistakes

Mistakes fixed and added in wp_kses back in. Might be too strong for
some people's liking.
gah!

undid cache.php
Merge pull request #18 from princezuda/master

manage_options commit