Panic on passwords without percent encoding

[millerjs]

Passwords that have not properly been percent encoded

fn main() {
    let _ = Connection::connect("postgres://user:%1*@localhost", SslMode::None);
}

result in a panic

thread '<main>' panicked at 'called `Result::unwrap()` on an `Err` value: InvalidHexCharacter { c: '*', index: 1 }', ../src/libcore/result.rs:746
note: Run with `RUST_BACKTRACE=1` for a backtrace.
error: Process didn't exit successfully: `target/debug/rspsql` (exit code: 101)