Add possibility to display output for executed command in command task

[janicalubos]

When command task finish succesfuly, stdout is discareded. It could be very helpful if there is possibility to change this behavior and display always full output for particular task. For example:

tasks:
- name: task1
command:
cmd: echo "This task is silent"
- name: task2
command:
cmd: echo "This task is displays this mesage"
verbose: true