Implemented cache only mode and updated unit tests

Implemented cache only / Fixes suggested by Jelle

Implemented cache only / Fixes suggested by Jelle

Implemented cache only / Fixes suggested by Jelle

Implemented cache only / Fixes suggested by Jelle

Implemented cache only / Fixes suggested by Jelle

Return empty array when no valid cachefile exists instead of exception

Return empty array when no valid cachefile exists instead of exception