* [DEV-376] Changed any instance of %v in format strings with a more specific format token
* [DEV-376] Fixed some more wrong formatting strings + removed redundant
cast
* [DEV-376] Added fmt.Sprintf where it was missing
* [DEV-376] use %s for util.Amount, to invoke .String()
* [DEV-376] Some more fixes in format strings
* [DEV-376] fixed mruinvmap_test to expect the correct behaviour
* [DEV-97] Moved github.com/daglabs/btcutil into github.com/daglabs/btcd/btcutil.
* [DEV-97] Updated Gopkg.toml to no longer refer to btcutil.
* [DEV-97] Renamed btcutil to util.
Previously, rpctest would start a btcd node using the btcd executable
in the environment PATH. This caused difficult-to-find issues where
the code would be tested against an older version of btcd, or another
fork entirely. Now it compiles btcd the first time it is needed and
uses that fresh version when launching nodes.