Flaky test: Cucumber CLI scenarios

[artem-zakharchenko]

During Cucumber feature testing there are two CLI scenarios that are flaky. Both seem to timeout randomly, and I cannot draw a clear conclusion what causes scenarios timeout.

1) Scenario: Read and validate real raw HTTP message from STDIN - node_modules/gavel-spec/features/cli.feature:18
   Step: Then exit status is 0 - node_modules/gavel-spec/features/cli.feature:24
   Step Definition: test/cucumber/step_definitions/cli_stepdefs.js:30
   Message:
     function timed out after 5000 milliseconds
2) Scenario: Exit status for invalid message - node_modules/gavel-spec/features/cli.feature:27
   Step: Then exit status is 1 - node_modules/gavel-spec/features/cli.feature:39
   Step Definition: test/cucumber/step_definitions/cli_stepdefs.js:30
   Message:
     function timed out after 5000 milliseconds

See the TravisCI job

Mentioned scenarios must be reviewed, rewritten (if necessary), and stabilized.