1. Should we cache this?
2. Can we just use Ruby's multi-line string for this?

  ```ruby
  @busser_env ||= "BUSSER_ROOT=#{busser_root} " \
                  "GEM_HOME=#{busser_root}/gems " \
                  "GEM_PATH=$GEM_HOME:/opt/sdk/juniper/lib/ruby/gems/1.9.1" \
                  "..."
  ```

3. Did you mean to add juniper stuff here? Not sure this is a good pattern to follow. If we need to extend the path, we should provide a way for the drivers to do that.