[Codeplex #1743]: Remove ATOM Support in WebAPI V4

Remove ATOM support in WebAPI V4 owing that ATOM is not in OData V4
standard currently and it is not fully support in OData V4.
[Codeplex #1904]: Migrate to ODL V6.3

ODL 6.3 is released and available on nuget along with the source code.
Here is the change summary of ODL in this release:
1. Fix a bug for serializing floating-point values to NaN, INF, and -INF.
2. EdmLib & ODataLib now supports model reference.
3. ODataLib now supports reading and writing delta response.
4. EdmxReader supports ignoring the unknown attribute/element in new
TryParse API.
5. ODataUriParser adds support for parsing relative Uri without service
root

So, The summary in this migration is:
1. Update to ODL V6.3 package
2. Fix the test cases.
port to ODL parser to parse path and template
support dollar id to specify the key of reference of entities
Adding support for overriding unobtrusive validation defaults

Work Item: 1502
Fix 1839 : Add support to Requesting Entity References
1907: ODataPathRouteConstraint.Match cannot get correct serviceRoot
This will fix IIS error on test branch.