Add support for adding view options in config

When using the default server, in addition to the default options
(optimize, reload and cachebust), additional options can be configured
in the config file, and are available as global variables in the views.

Example with jade:

    # views/index.jade
    body
      div.message
        p= message

    # mimosa-config.coffee
    server:
      views:
        compileWith: 'jade'
        options:
          message: "message from config file"