Log Message:
Update ruby-sshkit to 1.13.1.

## [1.13.1][] (2017-03-31)

### Breaking changes

  * None

### Bug fixes

  * [#397](https://github.com/capistrano/sshkt/pull/397): Fix NoMethodError \ 
assign_defaults with net-ssh older than 4.0.0 - \ 
[@shirosaki](https://github.com/shirosaki)

## [1.13.0][] (2017-03-24)

### Breaking changes

  * None

### New features

  * [#372](https://github.com/capistrano/sshkit/pull/372): Use cp_r in local \ 
backend with recursive option - \ 
[@okuramasafumi](https://github.com/okuramasafumi)

### Bug fixes

  * [#390](https://github.com/capistrano/sshkit/pull/390): Properly wrap Ruby \ 
StandardError w/ add'l context - \ 
[@mattbrictson](https://github.com/mattbrictson)
  * [#392](https://github.com/capistrano/sshkit/pull/392): Fix open two \ 
connections with changed cache key - [@shirosaki](https://github.com/shirosaki)