Push winrm support out to a separate Train plugin

[clintoncwolfe]

Description

We have discovered that to install support for winrm, the gem must compile native extensions (ffi). This is inappropriate for many InSpec users, and the train-core was intended to provide a compile-free gem install.

As the Train project has a goal of moving transports into plugins, one solution is to push the winrm code into a plugin, then have projects like Chef DK depend on train-core and train-winrm. InSpec would depend on train and train-winrm.

Train and Platform Version

2.0.8

• inspec depends on train-winrm

[clintoncwolfe]

Merged on #448