docs: Describe conventions
Improve docs
Set Content-Type header
Move server into main.go

Keep it simple for now.
docs: Improve
Implement naive Insert/List
Working file db
Add categories, simplify decoding, fix bugs
db: fix nil pointer exception
Use 409 Conflict
Basic validation skeleton
Implement RFC3339Z time
initial timestamps and order

Still has a weird sorting bug.
Rename resource 'type' to 'kind'

Avoids problems with 'type' being a keyword in go.
Some yak shaving for the yaks