dctc: Sort the command in the help.

Closes #46.

* src/dctc/java/com/dataiku/dctc/Main.java: Use a TreeMap.
command: Correct short/long options swap.

Closes #45.

* src/dctc/java/com/dataiku/dctc/command/Command.java: Here.
command: Don't pad the usage messages.

* src/dctc/java/com/dataiku/dctc/command/Command.java: Here.
Make case insensitive the protocol name.

* src/dctc/java/com/dataiku/dctc/file/FileBuilder.java: Add a
  toLowerCase to the protocol input.
file builder: Clean naming (local -> file).

Closes #44

* src/dctc/java/com/dataiku/dctc/file/LocalFileBuilder.java: The file
  builder is the user interface. Hold a coherent naming. Authorize the
  the local protocol as an alias to file protocol.
* src/dctc/java/com/dataiku/dctc/file/LocalFile.java,
  src/dctc/java/com/dataiku/dctc/file/FileBuilder.java: Adjust.
list command: Just inform the implementation of the destination file
or directory.

* src/dctc/java/com/dataiku/dctc/command/ListCommand.java: Here.
* src/dctc/java/com/dataiku/dctc/command/Cp.java,
  src/dctc/java/com/dataiku/dctc/command/Dispatch.java,
  src/dctc/java/com/dataiku/dctc/command/Mv.java: Adjust.
ssh: Detect `Permission denied'.

Closes #47.

* src/dctc/java/com/dataiku/dctc/file/SshFile.java: Need to list the
  whole directory (with -a option pass to ls) and detect if the
  directory is empty or not.