add support for std::wstring, soci::binary and unified ODBC product type gathering

The pull request contains 3 commits primary dedicated to ODBC backend for:
- supporting ```std::wstring``` type additionally to ```std::string``` type
- supporting new ```soci::binary``` type to be able to bulk read/write blobs
- unified access for product type (by enum, name or vendor string)

Each commit set contains more detailed information.