Use httpcomponents fluent API in acceptance tests

By using the fluent API we can simplify the HTTP connection calls.

We no longer need to explicitly set the max connections per route and
max total connections. Internally the fluent API's Executor [1] uses
a PoolingHttpClientConnectionManager with maximum 100 connections per
route and a total maximum of 200 connections. These maximums are not
as high as the ones we were previously using, but those were most
likely over-estimated anyway.

[1] http://hc.apache.org/httpcomponents-client-ga/fluent-hc/apidocs/org/apache/http/client/fluent/Executor.html

Change-Id: Ibab7ff76736f9ba063df28addc9a786bbaaadfe7
4 files changed