* Add loglevel and logfile switch to `embark build`
* Support existing `loglevel` and `logfile` switch for `embark run/upload`
* make casing consistent for `loglevel` and `logfile`
* remove passing engine to `build()` and instead pass needed objects in options.
* prevent duplicate plugin initiation (above point)
* allow `Events` object to be passed to `Engine` constructor and `init()`
* prevent echo of upload commands to allow interception and control via logging