(maint) Capture stdout from tests

Test output is captured when running specs in parallel, but not in series like,
bundle exec rspec spec, so explicitly capture the output so it doesn't
pollute the test results.

Author: joshcooper

spec/integration/application/agent_spec.rb

@@ -1043,6 +1043,7 @@ def mounts
         expect {
           agent.run
         }.to exit_with(1)
+          .and output(/Info: Loading facts/).to_stdout
           .and output(
             match(/Error: Evaluation Error: Unknown variable: 'osfamily'/)
               .and match(/Error: Could not retrieve catalog from remote server: Error 500 on SERVER:/)

spec/unit/application/lookup_spec.rb

@@ -668,6 +668,7 @@ def run_lookup(lookup)
           expect {
             lookup.run_command
           }.to exit_with(0)
+           .and output(/This is in facts hash/).to_stdout
         end
       end
     end