adding dataclient.c and WarmupTests

Engine tests suite is collection of tests for
testing the eventually persistent engine(ep-engine)
component of Couchbase Server.

Change-Id: I84534ebb9b84388c79d26fa1252fe0e553c0a649
Reviewed-on: http://review.couchbase.org/39211
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Sundararaman Sridharan <sundar@couchbase.com>
Tested-by: Venu Uppalapati <venumahesh@gmail.com>