Xd 2145 - Authenticated shell support (apply after 1201)

Shell changes: …
* Use Apache HttpClient for authentication in the Shell
* admin config server' now supports the '--username' and '--password' parameters
* Supporting unit tests for HTTPS and authentication in the Shell
Do we intend to pass username and password as commandline argument for the `xd-shell`command? I don't see it working. Even when I pass "--host xxxx" it fails as:
```
Sep 26, 2014 11:33:02 AM org.springframework.shell.core.SimpleParser commandNotFound
WARNING: Command '--host localhost' not found (for assistance press TAB)
```
Given this already fails, I think we can always expect user sets the username, password from within XD shell. If you agree, may be we can get rid of these getter methods for username/password.