Rename dev to devnet

--dev still works thanks to the |. Acheieves a personal preference of 
mine with some historical meaning.

substrate/node/src/chain_spec.rs

@@ -45,7 +45,7 @@ pub fn development_config() -> Result<ChainSpec, &'static str> {
     // Name
     "Development Network",
     // ID
-    "dev",
+    "devnet",
     ChainType::Development,
     || {
       testnet_genesis(

substrate/node/src/command.rs

@@ -38,7 +38,7 @@ impl SubstrateCli for Cli {
 
   fn load_spec(&self, id: &str) -> Result<Box<dyn sc_service::ChainSpec>, String> {
     match id {
-      "dev" => Ok(Box::new(chain_spec::development_config()?)),
+      "dev" | "devnet" => Ok(Box::new(chain_spec::development_config()?)),
       "local" => Ok(Box::new(chain_spec::testnet_config()?)),
       _ => panic!("Unknown network ID"),
     }