refactor: nicer logging when watching for changes / hot reloading

[edvald]

Closes #402 and #237

[drubin]

@edvald The formatting looks a little broken if we make a change to a garden.yml file the gear icon feels like its in the middle of nowhere and the -> don't line up.

Before with no output (it just carries on reloading)

This branch after making a change to garden.yml

This is reproducible in the hot-reload example.

Just run garden-local dev and make a change to any garden.yml file.

[edvald]

Good catch! I'll fix that