Swap boost sourceforge download url for github repo.
Swap boost sourceforge download url for github repo.

GroestlCoin/libgroestlcoin-explorer,tuomassiren/libbitcoin-explorer,GroestlCoin/libgroestlcoin-explorer,cancoin/libbitcoin-explorer,cancoin/libbitcoin-explorer,GroestlCoin/libgroestlcoin-explorer,tuomassiren/libbitcoin-explorer