Add command to create releases.
Extract editor logic from the pull request commands.
Create a new release based on the local branch.
Add the release command do the help.
Move the editor the github package.

This avoids double importing issues.
Add release creation and assets uploading.
Read only part of the asset to detect the content type.
Invert flags order.
Remove double status output.
Use a more generic message when the edit fail.
Write a message in the editor showing what you're doing.
Use WaitGroup to upload each asset in a different goroutine.
Remove double isDir helper.
Move `isEmptyDir` to the command utilities.

Removes duplicated test helper.
Assert directory truthy.
Do not double return errors.
Identify each message editor separatedly.
Update go-octokit.
Use the upload service in octokit.
Merge branch 'master' into gh_release

* master:
  Gramma issue in README
  Bump homebrew-gh which fixes sha and download path
  Bump homebrew-gh submodule to 1.0.0
  Bump version to v1.0.0
  Make it explicit that multiple credentials are allowed
  Quote path
  Add link to available setting
  Add autoupdate setting to README
  Make sure we load the deprecated configuration and override it with the new one.
  Save the new config after assigning the credentials.
  Save the configuration with the new format when the deprecated one is detected.
  Update versions automatically when autoupdate is set to true.