update to Substrate 2.0 (#181)

auction/Cargo.toml

auction/src/mock.rs

benchmarking/Cargo.toml

benchmarking/src/tests.rs

currencies/Cargo.toml

currencies/src/mock.rs

gradually-update/Cargo.toml

gradually-update/src/mock.rs

oracle/Cargo.toml

oracle/rpc/Cargo.toml

oracle/rpc/runtime-api/Cargo.toml

oracle/src/mock.rs

prices/Cargo.toml

schedule-update/Cargo.toml

schedule-update/src/mock.rs

tokens/Cargo.toml

tokens/src/mock.rs

traits/Cargo.toml

utilities/Cargo.toml

utilities/src/linked_item.rs