zkInterface HTTP servers and benchmark

File	Description
`*-server`	HTTP server executables wrapping various proof systems.
`benchmark/src/main.rs`	Run various benchmarks and report average runtimes.
`benchmark/src/circuit.rs`	Generate test circuits of different sizes.
`benchmark/src/runner.rs`	Request proofs from the servers with an HTTP client.

Run the benchmark

cd benchmark
cargo bench