TOMOYO: Rename directives.

Convert "allow_..." style directives to "file ..." style directives.
By converting to the latter style, we can pack policy like
"file read/write/execute /path/to/file".

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>