Update dependencies to latest versions

[Tiffany Bennett]

• chrono (significant breaking changes)
  • chrono-tz
  • chrono-humanize
• serde
  • serde_derive - not needed anymore now that proc macros exist
• sandboxing -- should be moved into rink-web, also there might be better alternatives for sandboxing than libc rlimit these days
  • ipc-channel (removed)
  • libc (removed)
• linefeed (significant breaking changes)
• xml-rs -- should look into replacing this with something that has xpath
• json -- should use serde for this probably
• reqwest