[GH-5] major overhaul of API layer and first client implementation in fetcher app
[GH-5] more API rework; CLI app now using proper API
[GH-5] port web client index page to proper API
[GH-5] start of web client sequence controller refactor
[GH-5] note on null return type
[GH-5] ensure API Client propagates response errors up the chain
[GH-5] various todo notes and first step towards translating null result into proper API error
[GH-5] implement remaining web calls at API layer
Merge branch 'api-rework'