Use GitLab Pages v0.4.2

What does this MR do?

Updates GitLab Pages to v0.4.2

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Support for precompressed .gz content in GitLab 9.2

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together