Network.URI now correctly chosen from network or network-uri
Network.URI now correctly chosen from network or network-uri

In network-2.6 the Network.URI module was split off from the network
package into the network-uri package. This commit means that rdf4h
automatically gets Network.URI from the right package. See the
documentation at:
http://hackage.haskell.org/package/network-uri

Fixes robstewart57/rdf4h#14

ddssff/rdf4h,jutaro/rdf4h,LeifW/rdf4h,cordawyn/rdf4h