Upgrading plugin for rundeck 3.x compatibility

Merge pull request #5 from sjrd218/plugin-metadata

Add extra plugin metadata

Adding ssh config at node level

• Adding ssh config options at node level (for example to set the connection port per nodes)
• For docker example, one of the nodes will have the ssh port set on a custom value (2223).

First release

1.0.0

Adding a docker example to test bastion plugin