Option to hide commands from stderr and ansible log

**Syntax:** 
*hide: true*

**Description:** 
Hide commands from stderr and ansible log. This will hide command arguments as well when used in verbose mode. This option would be helpful when you are running some command which requires passwords and you don't wont ansible to display it on your screen or ansible log.

**NOTE:**
 Ansible already has a way to hide passwords, but that works only when you pass something like "password=mypass". It will scan your command and search for a 'password' string, which might not be the case for all use cases.

**Example: ** 

    - name: Display facts
      command: facter -p
      hide: true

**Output:**

    <HOST> REMOTE_MODULE command ARGUMENTS_HIDDEN
    changed: [HOST] => {"changed": true, "cmd": "COMMAND_HIDDEN", "delta": "0:00:01.433558", "end": "2014-06-02 16:26:58.353121", "rc": 0, "start": "2014-06-02 16:26:56.919563", "stderr": "", "stdout": ""}