copy: Check the date before setting it.

Closes #74.

* src/dctc/java/com/dataiku/dctc/copy/DirectCopyTaskRunnable.java:
  Check if the input generalized file has a date.
clo: Correct the managing of sort option.

Closes #75.

* src/dctc/java/com/dataiku/dctc/clo/Parser.java: Skip the next good
  argument.
gfile: Correct sort function.

Close #79.

* src/dctc/java/com/dataiku/dctc/file/AbstractGFile.java: Don't delete
  numbers on the compare function.
alias: Resolve escaped command even if in non-interactive.

Closes #78.

* src/dctc/java/com/dataiku/dctc/configuration/Alias.java: Move a
  block of code.