Replace deprecated Bounded::max_value with Int::max_value
Remove unused `extern crate time`
Add dev-dependency for extern time library

Fixes a deprecation warning, see:
https://github.com/rust-lang/rust/commit/fcd05ed99ff0aa6157e427a698ac53dbc450135f
Merge pull request #438 from nicholasbishop/bishop_fix_warnings

Warning fixes