Add per device rate metrics for instances

This change add pipline configuration support to gether per device
rate metrics for instance. The per device rate metrics for instances
is transform from the metrics of per devices for instances by adding
metrics to disk_pipline in pipline cfg. These metrics will be independent
of the support of per devices rate metrics provided by inspector.

This thange will add the following metrics:
  - "disk.device.read.bytes.rate"
  - "disk.device.read.requests.rate"
  - "disk.device.write.bytes.rate"
  - "disk.device.write.requests.rate"

Change-Id: I908ab40cc77966238944060e33603c5f4c440634
Add Sample ReST API path in webapi document

Sample type has been described in webapi document, but API path is
missing, this patch fixes it.

Change-Id: I09248aac036479c9ccd250824de4df05713bfaa1
Closes-Bug: #1388507
VMware: Enable VMware inspector to support any port

If vCenter is configured to use any port other than 443,
the inspector fails to connect to vCenter.
This patch adds a configurable parameter host_port in
ceilometer config under vmware section.

DocImpact
Change-Id: I9035b32ffbc58bb1801b02abdce4bc83a3427308
Closes-Bug: #1387050
Merge "Add Sample ReST API path in webapi document"
Merge "Add per device rate metrics for instances"