Split rm into rm/rmdir, added consts for dangling strings

[grantseltzer]

This will now make it so you have to use rmdir for directories and rm for files. A separate PR can address needing to recursively remove directories.

Also exported strings "folder" and "file" to consts.go, they're used elsewhere but they can be changed as they're gotten to.

Signed-off-by: Grantseltzer grantseltzer@gmail.com

[grantseltzer]

@diwakergupta I made changes based on your input. Let me know if you think of anything else or want me to clean up the commit history

[diwakergupta]

Thanks!