Remove guard-yard
Make spec syntax 1.8.7 compatible
Make OTP delivery regex 1.8.7 compatible
Backports, spec tweaks for pubsubhubbub compat for 1.8.7
1.8.7 compat for Releases
Run CI on 1.8.7
Do not include specs in gemspec

Fixes #313. While shipping specs with the gem is preferable, running the
test suite requires some additonal setup anyway so developers will end
up needing the full source from GitHub.
Merge pull request #317 from octokit/one-eight-seven

Restore 1.8.7 compatibility
Merge pull request #318 from octokit/exclude-specs-from-gemspec

Do not include specs in gemspec
Bump for release
Release 2.3.0