RUBY-663 RUBY-664 only suppress OperationFailure and raise most
  recent one when doing batch inserts with continue on error
minor: replacing redcarpet with kramdown to resolve ruby 2.0 install errors
RUBY-650 move check for exhaust option into method
RUBY-650 raise exception for exhaust + limit combo
RUBY-650 be less verbose and improve style
RUBY-657 support URI encoded usernames and passwords
RUBY-658 fixing issue with default db from connection uri