Revert "remove encryption testfile in make clean"

This reverts commit 51beed213f04d00e4362dc144dfe4edc7de5539a.
Merge branch 'master' of https://github.com/ianks/fuse-encrypted-filesystem
Merge branch 'master' of https://github.com/ianks/fuse-encrypted-filesystem
updated files in mnt directory