custom AWS url, support for ActiveSupport::TimeWithZone & use RFC3339 for time objects

[gouthamvel]

• Custom AWS url useful for testing
• Support for ActiveSupport::TimeWithZone: useful when indexing active record.
• Convert Time/Date objects to AWS recommended format instead of timestamp.

[gouthamvel]

I think makes more sense to merge this in 1.0. didn't notice that branch. Closing this.