use srm if available, this is OSX's secure remove utility
add blackbox_shred_all_files that shreds decrypted versions of any encrypted file, this will discard current changes
cleanup some mis-named things and remove dead var
Merge pull request #23 from mavenlink/add-osx-srm-support

use srm if available, this is OSX's secure remove utility
Merge pull request #22 from mavenlink/add-shred-all-files-command

add blackbox_shred_all_files
Use -- to prevent potential issues with funny file names