[Apache] Add exclusions

https://trac.torproject.org/projects/tor/ticket/13146
[Apache] Split false MCB coverage
[Apache] Add comments
[Box] Add exclusion
[Courage Campaign] Remove secure, mixedcontent → default_off

secure no longer exists.
[Courage Campaign] Add comment
[Dropbox] Add/amend comments
[F-Secure] Split problematic coverage

Conflicts:
	src/chrome/content/rules/F-Secure.xml
[Facebook] Add comment

Conflicts:
	src/chrome/content/rules/Facebook.xml
[Leo.org] Exclude bar

https://trac.torproject.org/projects/tor/ticket/12135

Conflicts:
	src/chrome/content/rules/Leo.org.xml