Add minor enhancements to jmeter configuration

Add minor enhancements to jmeter configuration

- Add user-agent field to jmeter config yaml and jmeter jmx
template that can be configured per URL in testplan
- Add duration time that can be used in combination with
ramp time. Duration is the total time of the test while
ramp time governs how much time is allotted to establish
all configured requests/connections
- Explicitly define clover-jmeter-master service name with
default namespace for clover-controller in clover-system
namespace to reach
- Add missing request_counts.html file

Change-Id: I5e2d388db0b73ea6c28482c94c33cc2a01f1b52e
Signed-off-by: earrage <eddie.arrage@huawei.com>