MongoDB Ruby Driver v1.6.0

• Added Gemfile
• ReplSetConnection seed format is now array of 'host:port' strings
• Added read preference :secondary_only
• Added ability to log duration -- enabled by default (Cyril Mougel)
• Added read_only option for DB#add_user (Ariel Salomon)
• Added :collect_on_error option for bulk-insert (Masahiro Nakagawa)
• Added and updated URI options (now case insensitive)
• Bug fix for ReplSet refresh attempting to close a closed socket
• Default op_timeout for ReplSetConnection is now disabled (was 30 seconds)
• Support db output option for map reduce (John Ewart)
• Support for keeping limited versions of files using GridFS (VvanGemert)