Some formatting in Aws.Core - hope nobody minds
SignedQuery should respect explicity body and content-type choices

A PostQuery used to override any explicityly given Body and
Content-Type choices in the SignedQuery. I belive this is to be
erroneous, as it simply overrode explicit selections due to a
PostQuery, which is particularly impossible to deal with when
implementing AWS version 4 signing.

It now enforces the PostQuery defaults *only* if the explicit
selections are missing.
The first operational building blocks of a DynamoDB implementation
Add PutItem for DynamoDB + better type conversion
Improve documentation of this first iteration of DynamoDB functionality
Merge remote-tracking branch 'refs/remotes/aristidb/master'
Get everything working again
Add DynamoDB UpdateItem command
Merge DynamoDb parts with upstream work

Merge remote-tracking branch 'refs/remotes/aristidb/master'

Conflicts:
	Aws/Core.hs
	Aws/DynamoDb/Commands.hs
	Aws/DynamoDb/Core.hs
	aws.cabal
More DynamoDb work and get DynamoDb example working
Upgrade conditionals to latest API
Make PrimaryKey more uniform and use the standard Attribute
UpdateItem reuses the Attribute type
Simplify the Item type for usability
Fill several documentation gaps in DynamoDb
Oops, add back the 'item' convenience packer
Use Proxy instead of undefined, add more DVal instances
Remove leftover constraints
Replace DVal with the nicer DynVal interface

This eliminates the need to write both a, [a] and Set a instances via
a Type Family.
Add Word instances + documentation