client:

- SSL passphrases are zeroed from command line arguments and no longer show up in "ps" output. However, you can still retrieve the length of the password from the "ps" output.
- If no value for the SSL --passphrase options is given, the user will be prompted for it.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@2911 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534