add v0.707.2.0 Changes entry
support raw BSON in a MongoDB::BSON::Raw class
add HashLike type
load MongoDB::WriteConcern in _Types
rename DocumentSizeError to general DocumentError
refactor database error throwing into _LastError role
add classes, roles and results for database ops
use new op classes for all operations except bulk
rename WriteResult to BulkWriteResult
Implement bulk write with op classes
remove old database operation code
simplify bulk API implementation

The original role decompostion was intended to allow reuse with a
future "fluent" API.  As the fluent API has been shelved, the
decomposition in unnecessary complexity.
rename BulkWriteResult attributes to match CRUD API

The legacy names are added as an alias for compatibility.
rename BulkWriteResult _parse to _parse_cmd_result
tidy code and docs
add assert documentation to CommandResult
PERL-93 implemented awaitData
PERL-259 implemented write commands for MongoDB 2.6+

This merge refactors all database operations into specialized "operation
classes".  The API classes no longer have as many details of database
operations; instead, they create an operation object and hand it off to
the client for execution.  Operation classes have an "execute" method
that takes a link to a server and returns an appropriate result object.
PERL-423 improved documentation of cursor snapshot mode
PERL-401 fixed index creation to always have a non-zero write concern