Add component support for individual teams (like tags)

[jvperrin]

This adds component support so that components can be set per-team in sensu_handlers::teams. This is useful since the jira project is generally set per-team and components are required per-project, so being able to set components (like tags) per-team is useful.

I also changed the code for picking components to be a bit different and more similar to the way labels/tags are currently constructed:

[
  *@event['check']['component'],
  *team_data('component'),
].uniq.reject(&:nil?)

Nicely enough, this handles nil, various values, and arrays as values without problems:

irb(main):001:0> [*nil]
=> []
irb(main):002:0> [*5]
=> [5]
irb(main):003:0> [*[1, nil, 3]]
=> [1, nil, 3]
irb(main):004:0> [*5, *nil, *[1, 2, 'test']].uniq.reject(&:nil?)
=> [5, 1, 2, "test"]

I tested this by editing /etc/sensu/conf.d/handlers/jira.json on an admin server in dev and adding a default component to a team for testing and then using a technique like in #129 to make test tickets (but without a component explicitly set).