ls: Align when listing display.

* src/dctc/java/com/dataiku/dctc/command/Ls.java: Here.
alias: New command. Just display the defined alias.

* src/dctc/java/com/dataiku/dctc/command/Alias.java: Here
* src/dctc/java/com/dataiku/dctc/Main.java: Add to the command list.
* src/dctc/java/com/dataiku/dctc/configuration/Alias.java: Add a
  getter for the alias list.
alias: Don't resolve alias when non interactive session.

* src/dctc/java/com/dataiku/dctc/configuration/Alias.java: As bash.
alias: Don't delete alias is multiple alias section.

* src/dctc/java/com/dataiku/dctc/configuration/Configuration.java: Use
  getNotNull function.
rename: setAlias -> addAlias.

* src/dctc/java/com/dataiku/dctc/configuration/Alias.java: Correct the
  name to understand the right behavior of the function.
style: Add missing spaces.

* src/dctc/java/com/dataiku/dctc/configuration/Configuration.java:
  Here.
alias: Add alias if argument(s) is given.

* src/dctc/java/com/dataiku/dctc/command/Alias.java: Here.
alias: Update the news.

* News.txt: Here.
du: New command.

* src/dctc/java/com/dataiku/dctc/command/Du.java: Here.
* src/dctc/java/com/dataiku/dctc/Main.java: Add to the command list.
* News.txt: Update.
s3: Correct getChildrenOf.

* src/dctc/java/com/dataiku/dctc/file/S3File.java: And don't puth the
  bucket to this function.
find: Don't make an NullPointerException when no kind is defined.

* src/dctc/java/com/dataiku/dctc/command/Find.java: Here.
du: More options.

* src/dctc/java/com/dataiku/dctc/command/Du.java: --all, --max-depth,
  --summarize, --total.
gs: Correct optimization bug.

* src/dctc/java/com/dataiku/dctc/file/GSFile.java: recursiveFileList
  could be null, in this case, don't file: already done.