Description of problem:
Undertow metrics "Processing Time", "Processing Time per Minute" and "Max Processing Time" do not have units defined in the graph. According to the EAP code, "Processing Time" and "Max Processing Time" are shown as nanoseconds. However, metric graphs in our UI do not show unit on the Y axis and collected numbers are huge - see attached processing-time-per-minute.png screen shot [1].

Additionally, it seems that we don't show units for all other metrics - see "Bytes Sent per Minute" graph on the same processin-time-per-minute.png screen shot.   

Version-Release number of selected component (if applicable):
RHQ 4.12

How reproducible:
Always

Steps to Reproduce:
1. Install RHQ;
2. Start and import EAP 7 server into RHQ inventory;
3. Enable statistics on the EAP 7 server by executing:

    /subsystem=undertow:write-attribute(name="statistics-enabled",value=true)

4. Enable processing-time collection by setting "record-request-start-time" to true:

    /subsystem=undertow/server=default-server/http-listener=default:write-attribute(name="record-request-start-time",value=true)

5. Create requests/load on this http-listener


Actual results:
Huge numbers are shown in the "Processing Time per Minute" graph and without unit - for instance 49990188766.4934 

Expected results:
The value 49990188766.4934 - is shown as seconds and the graph shows correct unit.