RFR: 446: Adhere to GitHub rate limits [v2]

[Robin Westberg]

> Hi all,
> 
> Please review this change that ensures that rest requests using a certain account are not performed concurrently. It
> also rate-limits non-GET requests to one per second (per account).
> Best regards,
> Robin

Robin Westberg has updated the pull request incrementally with one additional commit since the last revision:

  Fix failing test

-------------

Changes:
  - all: https://git.openjdk.java.net/skara/pull/690/files
  - new: https://git.openjdk.java.net/skara/pull/690/files/aa0270a2..26e24467

Webrevs:
 - full: https://webrevs.openjdk.java.net/skara/690/webrev.01
 - incr: https://webrevs.openjdk.java.net/skara/690/webrev.00-01

  Stats: 28 lines in 1 file changed: 14 ins; 11 del; 3 mod
  Patch: https://git.openjdk.java.net/skara/pull/690.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/690/head:pull/690

PR: https://git.openjdk.java.net/skara/pull/690