Add cargo-clippy

[kbknapp]

This requires a nightly compiler - so the blocking issue is a way to conditionally compile a binary

[kbknapp]

Postponed until #4 is solved

[kbknapp]

Update

I'm not worried about requiring nightly rustc anymore. cargo-clippy was actually briefly included with this package...but prematurely so. It installed and compiled just fine, but turns out actually runny cargo-clippy wasn't possible because it requires the clippy lib at runtime external to link against. So until that problem is solved, this will have to remain postponed.