Add options for command, logDir, logFile, errFile

Addresses issue #4. Adds a few options:

##### index ```string```

The option specifies the main application file that will be run under a daemon using `forever`.

##### command ```string```

The command to execute, defaults to 'node'. Set this to 'coffee' to run
coffeescript applications.

##### logDir ```string```

The directory log files are saved, defaults to 'forever'.

##### errFile ```string```

File stderr is logged into, defaults to 'err.log'.

##### logFile ```string```

File stdout is logged into, defaults to 'out.log'.