Changing host or port should regenerate server code

[aik099]

The Behat\Mink\Driver\NodeJS\Server::createTemporaryServer uses following options of the server:

• host
• port
• nodeModulesPath

Currently on change of nodeModulesPath causes temporary server code to be regenerated.

Propose to regenerate temporary server code also on host and port option change.

Separate issue (see #157) is created to prevent calling these methods on already running server, that would have no effect.

[stof]

See #161 for my proposal to solve it in a much better way (the case of a running server still need to be prevented even in my proposal)

[aik099]

Agreed that creating ENV-based server instead of PHP variable patching is better way.