global conf: Rename confFile -> confPath and add method confFile

* src/dctc/java/com/dataiku/dctc/configuration/GlobalConf.java: Here.
* src/dctc/java/com/dataiku/dctc/Main.java,
  src/dctc/java/com/dataiku/dctc/command/AddAccount.java,
  src/dctc/java/com/dataiku/dctc/configuration/CredentialProviderBank.java:
  Adjust.
structured conf: fix: Don't forget to check and set the configuration
file.

* src/dctc/java/com/dataiku/dctc/configuration/StructuredConf.java:
  Here.
gfile: setDate, implemented for local and ftp file.

* src/dctc/java/com/dataiku/dctc/file/AbstractGFile.java,
  src/dctc/java/com/dataiku/dctc/file/FTPFile.java,
  src/dctc/java/com/dataiku/dctc/file/GeneralizedFile.java,
  src/dctc/java/com/dataiku/dctc/file/LocalFile.java: Here.
style: spaces.
Add preserve date for Cp.

* src/dctc/java/com/dataiku/dctc/command/Cp.java: Here.
* src/dctc/java/com/dataiku/dctc/command/Edit.java,
  src/dctc/java/com/dataiku/dctc/command/Mv.java,
  src/dctc/java/com/dataiku/dctc/command/Sync.java,
  src/dctc/java/com/dataiku/dctc/copy/DirectCopyTaskRunnable.java,
  src/dctc/java/com/dataiku/dctc/copy/SimpleCopyTaskRunnableFactory.java: Adjust.