Add option to prompt hosts before executing task

This feature adds an option to prompt a list of the hosts that are about to be targeted before executing the task.

I think the most common pattern is to decorate tasks with hosts/roles rather than selecting hosts with the command line option. So without modifying fabfile or remember hosts to exclude/include, this feature simply gives the user the ability to target specific host(s) easily.

**Output example:**
```
0. All
1. 10.0.0.10
2. 10.0.0.11
3. 10.0.0.12
Select host(s) [0]
```