Updated some documentation in AWS::DataPipeline::Client.
Added support for AWS Direct Connect (2012-10-25).
Simplified the connection pool and addressed a few issues.

The default http handler (AWS::Core::Http::NetHttpHandler) used
internally a Net::Http::ConnectionPool class.  This was refactored
(and renamed to AWS::Core::Http::ConnectionPool).

* ConnectionPool.new will now return a previously build (shared)
  pool for the same options.

* ConnectionPool.new now tracks all pools, and you can get a list
  of them from ConnectionPool.pools.

* Moved Net::HTTP patch into aws/core/http/patch (this fixes
  100-continue bug in 1.9.3 and 2.0.0)

As part of this refactor a handful of configuration options were
removed from AWS::Core::Http::Request (e.g. ssl_ca_file, proxy_uri,
etc).  These attributes are now passed to the ConnectionPool
constructor instead and not tracked on each http request.
Fixed namespace bug in http patch (after move).
Loosened expired credential error matching to catch both ExpiredToken and RequestExpired.