Update version to 0.3.0-SNAPSHOT
Update session cleanup and disconnect
Factor out lock-machine and unlock-machine
Remove reflection warnings
Ensure model images are immutable before use (Fixes #46)
configure-network can now add port-forwarding rules to adapters.

Example: to configure an adapter that port forwards the host's port 8008 to the
guest's port 80:

(configure-network machine {:attachment-type :nat
                            :nat-rules [{:name "http", :protocol :tcp,
                                         :host-ip "", :host-port 8080,
                                         :guest-ip "", :guest-port 80}]})
Add import of vagrant .box urls to setup-model
Add get-network-adapters and get-network-interfaces

Add functions in manager and machine to get network interface and adapters as maps.
Remove clj-http dependency
Fix the virtualbox metadata

When options are supplied, merge them rather than rely only on the options
passed.
Add usage of public vagrant key for .box images
Enforce psssing of os-family, etc, for .box images

The information is unavailable in the .box file, so has to be supplied manually.
Add Vagrant support info on README.
Release v0.3.0-alpha.2