store initial challenge period (#65)

ismp/src/handlers/consensus.rs

@@ -118,6 +118,7 @@ where
     // Store the initial state for the consensus client
     host.store_consensus_state(message.consensus_state_id, message.consensus_state)?;
     host.store_unbonding_period(message.consensus_state_id, message.unbonding_period)?;
+    host.store_challenge_period(message.consensus_state_id, message.challenge_period)?;
     host.store_consensus_state_id(message.consensus_state_id, message.consensus_client_id)?;
 
     // Store all intermedite state machine commitments

ismp/src/messaging.rs

@@ -69,6 +69,8 @@ pub struct CreateConsensusState {
     pub consensus_state_id: ConsensusStateId,
     /// Unbonding period for this consensus state.
     pub unbonding_period: u64,
+    /// Challenge period for this consensus state
+    pub challenge_period: u64,
     /// State machine commitments
     pub state_machine_commitments: Vec<(StateMachineId, StateCommitmentHeight)>,
 }