Allow bytearrays to be stored as BLOBs.

Any object that is serialized is now put in a Serialization type then
serialized.

When sqldeserialize is called on a bytearray, it checks whether the
deserialized array is a Serialization and if so returns the object it holds,
otherwise returning the array.
Test sqlserialize and sqldeserialize more thoroughly.
Fix serialization in sqlreturn and more tests.

sqlreturn(::Any, ::Vector{UInt8}) was serializing values so any values passed to
sqlreturn(::Any, ::Any) were being serialized twice. The net result of this
being that they were returned as bytearrays.
Merge pull request #51 from quinnj/iss50

Allow bytearrays to be stored as BLOBs