(#3118) - Typo correction

Changed 'formally' to 'formerly' to indicate 'previously' or 'in the past'
(#3122) - img partial and retro applicaton
(#3120) - small edits to guide
(#3111) - change db.compact()'s return value back
(#3124) - Compress Images
(pouchdb/mapreduce#228) - fix phantomjs test

This is what's preventing the phantomjs
tests from running in Travis for express-pouchdb
and pouchdb-server.