Issue #375 - Only return Link header if GitHub gave it to us.
Issue #375 - Pull out unwanted params from Link headers.
Issue #375 - Account for GitHub not always sending us a Link header.
Issue #375 - Be less strict on whitespace when parsing Link.
Issue #375 - Improve comment for getRelValue early return.
Issue #375 - Address review nit.
Merge pull request #377 from webcompat/375/1

Seemingly unrelated, yet related commits improving our handling of Link headers