Potentially breaking changes

• The SSHKit DSL is no longer automatically included when you require it. This means you must now explicitly include SSHKit::DSL. See PR #219 for details. @beatrichartz
• SSHKit::Backend::Printer#test now always returns true PR #312 @mikz

New features

• SSHKit::Formatter::Abstract now accepts an optional Hash of options PR #308 @mattbrictson
• Add SSHKit::Backend.current so that Capistrano plugin authors can refactor helper methods and still have easy access to the currently-executing Backend without having to use global variables.
• Add SSHKit.config.default_runner options that allows to override default command runner. This option also accepts a name of the custom runner class.
• The ConnectionPool has been rewritten in this release to be more efficient and have a cleaner internal API. You can still completely disable the pool by setting SSHKit::Backend::Netssh.pool.idle_timeout = 0. @mattbrictson @byroot PR #328

Bug fixes

• make sure working directory for commands is properly cleared after within blocks PR #307 @steved
• display more accurate string for commands with spaces being output in Formatter::Pretty PR #304 @steved PR #319 @mattbrictson
• Fix a race condition experienced in JRuby that could cause multi-server deploys to fail. PR #322 @mattbrictson