added --sha parameter for non-Travis compatibility

[nickmerwin]

When debugging an issue with @dokie I noticed that none of his builds were coming through from CircleCi with a commit SHA. When sending coverage data to Coveralls from Travis it's ok to omit that because we query their API to pull the commit info. But for other CI's it needs to be specified explicitly.

I've added SHA as the -s parameter here, but this could be refactored to pull git info directly from the environment. Here's how we do that in coveralls-ruby:

hash[:head] = {
  :id => ENV.fetch("GIT_ID", `git log -1 --pretty=format:'%H'`),
  :author_name => ENV.fetch("GIT_AUTHOR_NAME", `git log -1 --pretty=format:'%aN'`),
  :author_email => ENV.fetch("GIT_AUTHOR_EMAIL", `git log -1 --pretty=format:'%ae'`),
  :committer_name => ENV.fetch("GIT_COMMITTER_NAME", `git log -1 --pretty=format:'%cN'`),
  :committer_email => ENV.fetch("GIT_COMMITTER_EMAIL", `git log -1 --pretty=format:'%ce'`),
  :message => ENV.fetch("GIT_MESSAGE", `git log -1 --pretty=format:'%s'`)
}

hash[:branch] = ENV.fetch("GIT_BRANCH", `git rev-parse --abbrev-ref HEAD`)

Perhaps someone with more Elixir-foo could make that happen eventually.

Thanks!

[parroty]

Thanks, I wasn't aware on this point.