#17 Dirs with / don't work

[Misha Nasledov]

Dirs with / in their names cannot be cd'd to. Perhaps
the dir names need to be checked for /s and escaped
before they are used.

[Travis Reitter]

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user_id=346641

There are similar issues with downloading files with '/' in
the name (they can't be found by the client).

Perhaps files with '/' in the name could have the character
changed, too (set in the preferences, or something).