feat(semantic-release): complete for this formula

Semi-automated using https://github.com/myii/ssf-formula/pull/62

@noelmcloughlin This PR brings the implementation into line with the latest structure across semantic-release formulas. In includes:

The new method of working with Travis, as introduced in https://github.com/saltstack-formulas/template-formula/pull/175.
Lint errors corrected for both of the new linters introduced (salt-lint and rubocop).
Other minor issues with documentation and standard structures.

One thing I noticed that I didn't get time to resolve is the missing tofs block in pillar.example. Something like:

  tofs:
    # The files_switch key serves as a selector for alternative
    # directories under the formula files directory. See TOFS pattern
    # doc for more info.
    # Note: Any value not evaluated by `config.get` will be used literally.
    # This can be used to set custom paths, as many levels deep as required.
    # files_switch:
    #   - any/path/can/be/used/here
    #   - id
    #   - roles
    #   - osfinger
    #   - os
    #   - os_family
    # All aspects of path/file resolution are customisable using the options below.
    # This is unnecessary in most cases; there are sensible defaults.
    # Default path: salt://< path_prefix >/< dirs.files >/< dirs.default >
    #         I.e.: salt://template/files/default
    # path_prefix: template_alt
    # dirs:
    #   files: files_alt
    #   default: default_alt
    # The entries under `source_files` are prepended to the default source files
    # given for the state
    source_files:
      template-config-file-file-managed:
        - 'example_alt.tmpl'
        - 'example_alt.tmpl.jinja'

The source_files would need to be updated for all uses of files_switch throughout this formula. Since you're the most familiar with that, I'll leave that in your capable hands.

saltstack-formulas / iscsi-formula

feat(semantic-release): complete for this formula #30