[Feature] Use a logger instead of print statements

[dstansby]

Is your feature request related to a problem? Please describe.
In #74 I noticed that several print statements are used throughout the code as a form of logging.

Describe the solution you'd like
These messages to be piped through a proper logger (maybe napari has something built in that can be used?) so it's easy for users to configure whether the messages are turned on/off and where to output them to (e.g. a file or the terminal)

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

[adamltyson]

I think these should be turned off, and everything should be either pop-ups or info in the napari help bar. Thoughts?

[dstansby]

👍 definitely happy to turn them off if they're not very useful for users

[adamltyson]

They're useful, they just shouldn't be in the console (especially for the bundled app).