Issue #2822679 by MegaChriz: Improved documentation for options --file, --url and --stdin for the Drush command 'feeds-import'.

Issue #608408 by MegaChriz, andypost, queenvictoria, pcambra, twistor, ivanbueno, mparker17, kenorb, agnese.stelce, alan-ps, clemens.tolboom, TommyK, JurriaanRoelofs, ericduran, ShaunDychko, sir_squall, alex_b, markabur, Kasper Souren, eiriksm: Added drush integration for Feeds.