Show available actions for info

**Feature description:**

```info``` now displays available actions when an auxiliary or post module is being used. Previously, it would show only the available targets if an exploit module was being used.

**Verification steps:**

- [ ] ```use``` an auxiliary module with actions
- [ ] ```info``` and see that available actions are displayed
- [ ] ```use``` an auxiliary module without actions
- [ ] ```info``` and see that no available actions are displayed
- [ ] ```use``` a post module with actions
- [ ] ```info``` and see that available actions are displayed
- [ ] ```use``` a post module without actions
- [ ] ```info``` and see that no available actions are displayed
- [ ] ```use``` an exploit module
- [ ] ```info``` and see that available targets are still displayed

**Sample run:**

```
msf auxiliary(chromecast_youtube) > info

       Name: Chromecast YouTube Remote Control
     Module: auxiliary/admin/chromecast/chromecast_youtube
    License: Metasploit Framework License (BSD)
       Rank: Normal

Provided by:
  wvu <wvu@metasploit.com>

Available actions:
  Name  Description
  ----  -----------
  Play  Play video
  Stop  Stop video

Basic options:
  Name     Current Setting  Required  Description
  ----     ---------------  --------  -----------
  Proxies                   no        Use a proxy chain
  RHOST                     yes       The target address
  RPORT    8008             yes       The target port
  VHOST                     no        HTTP server virtual host
  VID      kxopViU98Xo      yes       Video ID

Description:
  This module acts as a simple remote control for Chromecast YouTube.

References:
  http://www.google.com/intl/en/chrome/devices/chromecast/index.html

msf auxiliary(chromecast_youtube) > use post/linux/gather/enum_xchat
msf post(enum_xchat) > info

       Name: Linux Gather XChat Enumeration
     Module: post/linux/gather/enum_xchat
   Platform: Linux
       Arch:
       Rank: Normal

Provided by:
  sinn3r <sinn3r@metasploit.com>

Available actions:
  Name     Description
  ----     -----------
  ALL      Collect both the plists and chat logs
  CHATS    Collect chat logs with a pattern
  CONFIGS  Collect XCHAT's config files

Basic options:
  Name     Current Setting  Required  Description
  ----     ---------------  --------  -----------
  SESSION                   yes       The session to run this module on.

Description:
  This module will collect XChat's config files and chat logs from the
  victim's machine. There are three actions you may choose: CONFIGS,
  CHATS, and ALL. The CONFIGS option can be used to collect
  information such as channel settings, channel/server passwords, etc.
  The CHATS option will simply download all the .log files.

msf post(enum_xchat) >
```