All crispin clients should implement folder_names().
All crispin clients should implement folder_names().

This is a start towards hammering down the Inbox data store abstraction,
which will canonicalize the names and semantics of various folder names.

jobscore/sync-engine,ErinCall/sync-engine,EthanBlackburn/sync-engine,gale320/sync-engine,PriviPK/privipk-sync-engine,EthanBlackburn/sync-engine,rmasters/inbox,nylas/sync-engine,gale320/sync-engine,Eagles2F/sync-engine,jobscore/sync-engine,closeio/nylas,wakermahmud/sync-engine,ErinCall/sync-engine,Eagles2F/sync-engine,EthanBlackburn/sync-engine,ErinCall/sync-engine,wakermahmud/sync-engine,Eagles2F/sync-engine,gale320/sync-engine,wakermahmud/sync-engine,jobscore/sync-engine,gale320/sync-engine,closeio/nylas,rmasters/inbox,PriviPK/privipk-sync-engine,closeio/nylas,Eagles2F/sync-engine,closeio/nylas,nylas/sync-engine,ErinCall/sync-engine,jobscore/sync-engine,PriviPK/privipk-sync-engine,nylas/sync-engine,rmasters/inbox,nylas/sync-engine,rmasters/inbox,gale320/sync-engine,wakermahmud/sync-engine,PriviPK/privipk-sync-engine,Eagles2F/sync-engine,EthanBlackburn/sync-engine,EthanBlackburn/sync-engine,ErinCall/sync-engine,PriviPK/privipk-sync-engine,wakermahmud/sync-engine