drush 8.x-6.0-rc3

Changes since 8.x-6.0-rc2:

• Previous commit broke drush_sql_dump_file in instances where the remote dump-dir does not exist on the local machine. Fixed by re-applying the dump-dir after calling drush_tempnam
• #2044571 by greg.1.anderson: Allow command specific options in sites/default/drushrc.php to work consistently with rsync
• Command specific options were being applied for all commands.
• #2034731 by helmo: Fixed Collected code style fixes.
• drush_redispatch_get_options() no longer propogates options from the alias context, as doing so is in conflict with option validation for backend requests.
• #2044801 by greg.1.anderson, dmitry_bezer: Fixed Drush fails to synchronize to a remote site with empty database.
• Fixing a make test that broke due to a file remote file being removed.
• #2011966 by greg.1.anderson, Owen Barton: Added PHP_OS in drush status.
• #2044881 by kostajh: Fixed Fail gracefully if user-login is not run on a bootstrapped site.
• 2017189 by greg.1.anderson: Do not include options from alias records -unless- they are global options.
• Follow up to Issue #1936866 by jonhattan: Drush dl needs to put files in /modules or /themes, not /sites/all/whatever. Fix _pm_download_destination_lookup()
• #1295756 by moshe weitzman | Alan Evans: Drush ignores php item in site aliases which specifies the php binary to use.