1.9.0.rc1

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