Sigv4 support for S3 by lindsley
Fixes to get BJS working - hacks!
S3 domains are a wee bit non-standard between regions.

Just a bit.
Updated Elasticache to utilize SigV4.
Added conditional use of SigV4 to EC2.
Added conditional signing selection to S3.
Added notes about multipart uploads to S3.
Added encoding-type support to S3.
Added missing docs.
Merge branch 's3-encoding-type' into develop
Merge branch 'elasticache-sigv4' into develop
Merge branch 's3-mp-notes' into develop
Merge branch 'ec2-bjs' into develop
Merge branch 's3sigv4' into develop