Default boot_nodes to local node in build-spec (#1181)

* Default to local bootnode with build-spec

* Rexport libp2p stuff via network crate

* Remove unused imports and fix where formatting

* Remove spurious blank lines

* Remove unnecessary else clause

substrate/core/network-libp2p/src/secret.rs

@@ -25,7 +25,7 @@ use NetworkConfiguration;
 const SECRET_FILE: &str = "secret";
 
 /// Obtains or generates the local private key using the configuration.
-pub(crate) fn obtain_private_key(
+pub fn obtain_private_key(
 	config: &NetworkConfiguration
 ) -> Result<secio::SecioKeyPair, IoError> {
 	if let Some(ref secret) = config.use_secret {