use bracketed namespacing to allow embedding into HHVM systemlib
create MongoLog
add MongoTimestamp
MongoRegex::__toString should include flags.
substr can return false, but regex/flags must always be strings
fix exception throwing
add MongoBinData constants
implement MongoCollection::toIndexString
implement MongoClient::__toString
add new classes to composer
Merge pull request #17 from danslo/master

HHVM fixes v1