handle server response without "n" value

RUBY-676
Array#sort_docs to check written docs consistently

RUBY-676
bulk API deferred write concern tests moved to replica set

also improved match_document diagnostics now includes key

RUBY-676
sort_docs(docs) local method replaces Array#sort_docs

RUBY-676
writeConcernError legacy write operations difference

RUBY-676
writeConcernError should raise OperationFailure exception

RUBY-676
test_max_scan ala server jstest/maxscan.js

includes additional correctness mods for test suite

RUBY-676
test_max_scan remove server version dependent assertion

RUBY-676
Merge branch '1.x-stable-ruby-676' of https://github.com/gjmurakami-10gen/mongo-ruby-driver into gjmurakami-10gen-1.x-stable-ruby-676