Correct message display.

* src/dctc/java/com/dataiku/dctc/display/AbstractThreadedDisplay.java,
  src/dctc/java/com/dataiku/dctc/display/AbstractTransferRateDisplay.java: Here.
If a file has failed, put it also in the done list.

* src/dctc/java/com/dataiku/dctc/display/AbstractTransferRateDisplay.java: Here.
Print the number of fail.

* src/dctc/java/com/dataiku/dctc/display/SimpleDisplay.java,
  src/dctc/java/com/dataiku/dctc/display/ListDisplay.java,
  src/dctc/java/com/dataiku/dctc/display/LessSimpleDisplay.java: Here
Do not pass the FTPClient.

Closes #17.

* src/dctc/java/com/dataiku/dctc/file/FTPFile.java: Here.
ftp file: avoid NullPointerException.

* src/dctc/java/com/dataiku/dctc/file/FTPFile.java: Here.
ftp: Optimize the speed.

* src/dctc/java/com/dataiku/dctc/file/FTPFile.java: Speed up the
  transfer rate, don't know why.
Clean is Windows checks.

* src/dctc/java/com/dataiku/dctc/configuration/GlobalConf.java,
  src/dctc/java/com/dataiku/dctc/file/LocalFile.java:
  getProprety("os.name") -> GlobalConstants.isWindows
Alias for Dctc.

Add alias for Dctc. The aliases need to be defined inside a [alias]
marker in the configuration.file. The syntax is like the shell syntax
but without the quoting marks. An example:

[alias]
  ls=ls -G

* src/dctc/java/com/dataiku/dctc/configuration/Alias.java: Here
* src/dctc/java/com/dataiku/dctc/Main.java: Resolve alias.
* src/dctc/java/com/dataiku/dctc/configuration/Configuration.java: Add drop method.