Fix checking all zpools (#2)

[smuth4]

Also re-order checks so the ones that can go critical are checked first

Before:

$ /opt/sensu/embedded/bin/check-zpool.rb
sh: tank: not found
sh: tank2: not found
sh: tank: not found
sh: tank2: not found
sh: tank: not found
sh: tank2: not found
CheckZPool CRITICAL: zpool tank3
tank
tank2 has state pool: tank3
 state: ONLINE
  scan: scrub repaired 0 in XXXXXX with 0 errors on XXXXX config:

    NAME                                            STATE     READ WRITE CKSUM
    tank3                                           ONLINE       0     0     0
      raidz2-0                                      ONLINE       0     0     0
        gptid/disk                                  ONLINE       0     0     0

After:

$ /opt/sensu/embedded/bin/check-zpool.rb
CheckZPool CRITICAL: zpool tank2 has state DEGRADED

/opt/sensu/embedded/bin/check-zpool.rb -C 1
CheckZPool CRITICAL: capacity for zpool tank1 is above 1% (currently 60%), zpool tank2 has state DEGRADED, capacity for zpool tank2 is above 1% (currently 60%), capacity for zpool tank3 is above 1% (currently 60%)

Pull Request Checklist

Is this in reference to an existing issue?

2

General

• [x] Update Changelog following the conventions laid out here

• [N/A] Update README with any necessary configuration snippets

• [N/A] Binstubs are created if needed

• [x] RuboCop passes

• [N/A] Existing tests pass

Purpose

To fix issue #2

Known Compatibility Issues

None

[majormoses]

We also need a testing artifact

[smuth4]

Added to the description