Fix to some multiaccess methods missing const
See description

-Send and receive now happen on separate threads. Both threads will now
sleep permanently until they have something to do.
-Removed SetTimeout function
-Added ConnectionPtr and ConnectionWPtr typedefs
-Added Close() method to connections
-Fixed some UDP issues in async_network
See description

-Removed all instances of size_t fromm serialization to ensure
compatibility between 32bit and 64bit
-Fixed issues with MongoReplicable's generateUpdateQuery when dealing
with changes to arrays containing non-trivial types, as well as nested
arrays
-Added ability to serialize binary data using BINARY_NAME_PROPERTY,
TRANSIENT_BINARY_NAME_PROPERTY, and via
sprawl::serialization::prepare_data(char* val, uint32_t dataLength,
const std::string& name, bool persist);