Added storage base class.
Added storage base class.

Airbitz/libbitcoin,libtetcoin/libtetcoin-consensus,libmetrocoin/libmetrocoin-consensus,swansontec/libbitcoin,BWallet/libbitcoin,semyazza/libbitcoin,Airbitz/libbitcoin,swansontec/libbitcoin,BWallet/libbitcoin,Airbitz/libbitcoin,kaostao/libbitcoin,BWallet/libbitcoin,kaostao/libbitcoin,Airbitz/libbitcoin,libtetcoin/libtetcoin-consensus,libmetrocoin/libmetrocoin-consensus,swansontec/libbitcoin,GroestlCoin/libgroestlcoin,semyazza/libbitcoin,libtetcoin/libtetcoin-consensus,semyazza/libbitcoin,libtetcoin/libtetcoin-consensus,swansontec/libbitcoin,libmetrocoin/libmetrocoin-consensus,GroestlCoin/libgroestlcoin,GroestlCoin/libgroestlcoin,libtetcoin/libtetcoin-consensus,kaostao/libbitcoin,libmetrocoin/libmetrocoin-consensus,kaostao/libbitcoin,BWallet/libbitcoin,libmetrocoin/libmetrocoin-consensus,GroestlCoin/libgroestlcoin