Include code description in the output of failed controls

[alexpop]

Fixes #1093

Using the example profile in issue #1093, this is the output based on inspec master:

$ be inspec exec /tmp/t.rb -t ssh://root@ap-cc6.opschef.tv --password 'xxx'

Target:  ssh://root@ap-cc6.opschef.tv:22

  ✖  test-kernel_parameter-999: verify certain settings in sysctl (1 failed)
     ✖  expected: >= 18419238472
          got:    128
     ✔  Kernel Parameter net.core.somaxconn value should be > 100

Profile Summary: 0 successful, 1 failures, 0 skipped

and this is the output after the code change in this PR:

$ be inspec exec /tmp/t.rb -t ssh://root@ap-cc6.opschef.tv --password 'xxx'

Target:  ssh://root@ap-cc6.opschef.tv:22

  ✖  test-kernel_parameter-999: verify certain settings in sysctl (1 failed)
     ✖  Kernel Parameter net.core.somaxconn value should be >= 18419238472
     expected: >= 18419238472
          got:    128
     ✔  Kernel Parameter net.core.somaxconn value should be > 100


Profile Summary: 0 successful, 1 failures, 0 skipped

[alexpop]

Rebased and passing all tests!

[chris-rock]

Awesome, thanks @alexpop