helpers for Config.time and Config.uri

Adds `Config.time` and `Config.uri` type casters.

`Config.time` tries Time.parse, then on rescue falls back to our "split the string on dashes and splat into Time.utc" so you can set a time as '2012' and it will parse to Jan 1st, 2012 in UTC.

Also replaced some ternary operators with a simple `&&` clauses.