Provide dual support for API versions 2012-08-10 and 2011-12-05.

This is a combination of 15 commits.
Retrieve apiVersion from HTTP request header.

Adding request/result mappers between API Versions 1 and 2.

Finished V1-to-V2 request and result mapping methods.

Able to compile cloned/revised .dynamodbv2.model.transform classes.

Cloning and refactoring new V2 tests.

V2 tests all compile.

AlternatorItemTest runs with in-process client.

AlternatorTableTest runs with in-process client.

AlternatorQueryTest runs with in-process client.

AlternatorScanTest runs with in-process client.

AlternatorBatchItemTest runs with in-process client.

AlternatorMapperTest runs with in-process client.

Start fixing V2 JSON (un)marshallers.

All test working with JSON marshalling of requests/results.

Added com.michelboudreau.alternatorv2 namespace for new clients.
Update Read Me file with dual API version notes.
For .query treat null ScanIndexForward as true, per AWS-SDK NodeJS doc.
Implemented BETWEEN, BEGINS_WITH, CONTAINS scan filters (with tests).
Correct GE scan filter comparison direction. Set pom.xml to 0.5.2-SNAPSHOT
fix Conditinal test
generics
Merge pull request #2 from sashee/master

Fixed conditional update
Merge pull request #66 from rrutt/dual-api-versions

Dual api versions merging