Change default behaviour to not create release commit

[william-lee-epigenesys]

• Tag current commit with new release when using release command by default
• Do not create release commit by default
• Do not update config/version.rb by default
• Add EpiDeploy.create_release_commit option, default false to revert to the previous release behaviour
• Warn if config/version.rb exists to prompt deletion
• Allow creating a release with a dirty working tree or index using --allow-dirty flag

[ClearCarbon]

in lib/capistrano/tasks/branches.rb ensure that the error message "Cannot determine commit to deploy as BRANCH environment variable is not set and LATEST_RELEASE_TAG constant in version.rb could not be found" is adjusted to take into account the new behaviour