RFC: error interoperation
Updated FromError to not inherit Error

Per comment

  https://github.com/rust-lang/rfcs/pull/201#issuecomment-53007366

and meeting notes

  https://github.com/rust-lang/meeting-minutes/blob/master/weekly-meetings/2014-08-26.md
Updated Error to inherit from Send+Any
Merge remote-tracking branch 'aturon/error-chaining'
RFC 70 is error interoperation