add -R(recursive) option support and output a human-readable file mod…
Created by: xiaozhuai
add -R(recursive) option support and output a human-readable file mode like -rwxr-xr-x
-rw-r--r-- 1000 1000 18 .gitignore
-rw-r--r-- 1000 1000 75 .travis.yml
-rw-r--r-- 1000 1000 720 Cargo.lock
-rw-r--r-- 1000 1000 2326 Cargo.toml
-rw-r--r-- 1000 1000 1092 LICENSE
-rw-r--r-- 1000 1000 695 README.md
drwxr-xr-x 1000 1000 4096 src
drwxr-xr-x 1000 1000 4096 src/bin
-rw-r--r-- 1000 1000 5935 src/bin/basename.rs
-rw-r--r-- 1000 1000 12861 src/bin/cat.rs
-rw-r--r-- 1000 1000 1433 src/bin/chmod.rs
-rw-r--r-- 1000 1000 894 src/bin/clear.rs
-rw-r--r-- 1000 1000 2234 src/bin/cp.rs
-rw-r--r-- 1000 1000 19245 src/bin/cut.rs
-rw-r--r-- 1000 1000 2152 src/bin/date.rs
-rw-r--r-- 1000 1000 3515 src/bin/dd.rs
-rw-r--r-- 1000 1000 3125 src/bin/df.rs
-rw-r--r-- 1000 1000 2848 src/bin/du.rs