Feature/spend coconut (#1261)

* Add coconut verifier structure for coconut protocol in gateway

* Add endpoint for validator-api cred verification

* Remove unused signature field

* Register new endpoint

* Improve validator-api config handling

* Aggregate verif result from all apis

* Simplify aggregate functions

* Verify cred on apis correctly

* Introduced coconut bandwidth contract to validator client

* Fix rebase double import

* Fix clippy on non-coconut

* Add multisig contract address to validator client

* Refactor Credential struct

* Do bincode magic in the coconut interface

* Implement serialization for credential and remove bindcode

* Fix clippy and don't remove dkg

* Client release funds proposal

* Add wrapper for blinded serial number

Also compare theta with a blinded serial number (in base 58 form)
for future double spend protection.

* Only post blinded serial number to blockchain

* Validator api propose credential spending

* Fix wallet

* Gateway calls proposal creation

* Query for proposal in verify coconut

* Remove db from git

* Verify against proposal description

* Validator apis vote based on verification of cred

* Fix wallet fmt

* Execute the release of funds

* Fix translation between token and bytes

* Update CHANGELOG

explorer-api/src/client.rs

@@ -23,19 +23,10 @@ impl ThreadsafeValidatorClient {
 }
 
 pub(crate) fn new_validator_client() -> ThreadsafeValidatorClient {
-    let network = DEFAULT_NETWORK;
-    let mixnet_contract = network.mixnet_contract_address().to_string();
     let nymd_url = default_nymd_endpoints()[0].clone();
     let api_url = default_api_endpoints()[0].clone();
 
-    let client_config = validator_client::Config::new(
-        network,
-        nymd_url,
-        api_url,
-        Some(mixnet_contract.parse().unwrap()),
-        None,
-        None,
-    );
+    let client_config = validator_client::Config::new(DEFAULT_NETWORK, nymd_url, api_url);
 
     ThreadsafeValidatorClient(Arc::new(
         validator_client::Client::new_query(client_config).expect("Failed to connect to nymd!"),