Council motions for approving treasury proposals (#694)

* Treasury in runtime, generic approve/reject

* Add logic for council origin

* Add tests.

* Configurable number of members in EnsureMembers

* Fix grumbles

* Fix spelling

* Comment

substrate/substrate/runtime/system/src/lib.rs

@@ -45,7 +45,7 @@ extern crate safe_mix;
 
 use rstd::prelude::*;
 use primitives::traits::{self, CheckEqual, SimpleArithmetic, SimpleBitOps, Zero, One, Bounded,
-	Hash, Member, MaybeDisplay};
+	Hash, Member, MaybeDisplay, EnsureOrigin};
 use runtime_support::{StorageValue, StorageMap, Parameter};
 use safe_mix::TripletMix;
 
@@ -168,6 +168,14 @@ decl_storage! {
 	}
 }
 
+pub struct EnsureRoot<AccountId>(::rstd::marker::PhantomData<AccountId>);
+impl<O: Into<Option<RawOrigin<AccountId>>>, AccountId> EnsureOrigin<O> for EnsureRoot<AccountId> {
+	type Success = ();
+	fn ensure_origin(o: O) -> Result<Self::Success, &'static str> {
+		ensure_root(o)
+	}
+}
+
 /// Ensure that the origin `o` represents a signed extrinsic (i.e. transaction).
 /// Returns `Ok` with the account that signed the extrinsic or an `Err` otherwise.
 pub fn ensure_signed<OuterOrigin, AccountId>(o: OuterOrigin) -> Result<AccountId, &'static str>