Update to substrate alpha.7 release (#105)

* Update to substrate alpha.7

* Remove gas limit from contracts put code

* Rename SystemEvent::ReapedAccount to KilledAccount

* Log debug event received before attempting to decode

* Temporary registration of Balance type before #102 merged

* Show contract test errors, increase instantiate gas_limit

src/frame/system.rs

@@ -184,7 +184,7 @@ pub enum SystemEvent<T: System> {
     /// A new account was created.
     NewAccount(T::AccountId),
     /// An account was reaped.
-    ReapedAccount(T::AccountId),
+    KilledAccount(T::AccountId),
 }
 
 /// A phase of a block's execution.