Feature Request: Support custom title per test case

[titom73]

Type: Feature Request Name: Add Test's title support Goal: Provide a title for each test to be able to identify tests in logs.

Example:

check_state:
  - command: show bgp summary
  - iterate:
      xpath: '//bgp-peer'
      id: './peer-address'
      tests:
        - no-diff: peer-state
          info: "blah"
          err: "blah"
          title: "Title for the test case"

Output's example:

[...]
Tests Included: check_state
*************************Command is show bgp summary*************************
----------------------Performing {{Test case title}} Test Operation----------------------
[...]

[dgarros]

Looks similar to #76