Use Literal Blocks to write code sample in docstring

In python docstring, one should use Literal Blocks to write sample
code otherwise one gets build warnings and badly formatted documents.

Also, because sphinx treats the line which starts ".." as a comment,
this patch moves "..." to the end of the previous line.

Change-Id: I0bbd61d43daaffe9de579b1a6b50ea6826bdfd50
Partial-bug: 1277282
Do not strip 'glance://' prefix from image hrefs

pxe_utils.get_deploy_kr_info and drivers.modules.pxe._get_image_info
functions strip 'glance://' prefix from image references while it's
not necessary as Glance service can download images by such refs.
Also some refactoring done as these references are not just uuids.

Partially implements: blueprint non-glance-image-refs

Change-Id: Ie0d87c96c80dab23ea81011413600d9dbbf50177
Correct vmware ssh power manager

{_NodeName_} in list_running has to be replaced since the power manager
relies on it.

Now _get_hosts_name_for_node is called before list_running, so unit
tests are modified too.

Change-Id: I4a787039b7bc0f13c29455f041120e9e43e7c46b
Closes-Bug: #1400674
Updated from global requirements

Change-Id: I4b8a4ee5fce8f3d0e47e111fa16e03de603c5038
Update dev quick-start for devstack

The devstack section of the developer's quick-start documentation is
updated:
1. replaces the https://devstack.org link (doesn't work) with
   http://docs.openstack.org/developer/devstack/
2. clarifies how to configure usage of the PXE or agent driver

Change-Id: I2220f685c862832f73b28157355e11c7b49ce29b
Closes-Bug: #1400461
Merge "Updated from global requirements"
Updated from global requirements

Change-Id: Ie753774f865e2d40125bea988bf75d02097d03c1
Merge "Use Literal Blocks to write code sample in docstring"
Merge "Do not strip 'glance://' prefix from image hrefs"
Merge "Updated from global requirements"
Merge "Correct vmware ssh power manager"