Moved the file logic into addfile.sh so that it can handle when a file
should be commited, making sublimecommit.sh effectly just a loop without
any real logic in it.

Exclude Pre/Post edit commits from time test

If the commit message is "Pre/Post edit commit of file $file" addfile.sh
will bypass the test test so that it will pre-commit the file regardless
of age.

I've removed all git related checks, such as if is in repo, has a diff,
is not excluded etc and just let git handle it.

Moved all env vars out of sublimecommit.sh and addfile.sh into a
sublimecommit-env.sh file which should be updated by the user and placed
in their homeidr as .sublimecommit-env.sh

Updated readme file.