Add a joystick.log_in_development() function

[rglover]

This would be really handy. Logs are essential for development, but we don't want them in non-development environments. It'd be helpful to have a function that automates this like so:

import joystick from '@joystick.js/node';

joystick.log_in_development('something to log');

This would just be a wrapper with an env check around the native console.log().

[rglover]

Could also add joystick.log_in_staging() and joystick.log_in_production() as those things can happen for information beyond debugging.

[rglover]

All of the above may be good candidates for addition to #49.

[rglover]

Would be best to do this as joystick[log|warn|error|info]('something', ['development']) where the second argument is an array of environments to log the message in. If no environments are passed, it's assumed to be dev only.