Core library, v1

[applejag]

Based on RFC iver-wharf/rfcs#4, https://iver-wharf.github.io/rfcs/published/0004-core-lib-repo

• Logging (pkg/logger #10, GIN & GORM logging integration #11)
• Version model & endpoint (Added pkg/app/version.go and examples, changelog, and go.mod #2)
• Reading configuration (Config #4)

Logging should take use of the configuration reading. Below some proposition of environment variables:

WHARF_LOGGING_FORMAT=json
WHARF_LOGGING_LEVEL=warn
WHARF_LOGGING_LEVEL_HTTP_IN=debug
WHARF_LOGGING_LEVEL_HTTP_OUT=trace
WHARF_LOGGING_LEVEL_SQL=debug

Letting the user of this logging library be able to declare logging scopes and then map those to different configs is quite essential