Fixes disk size issue during image boot on Hyper-V

Fixes bug: 1135155

The local root disk size provided in the instance flavor was not properly
taken into account in the Hyper-V driver, this patches provides a
fix for this feature.

In order to resize VHD images with differencing disks (CoW), the cached
base disk is copied to a new file, which is resized to the size
specified in the flavor and cached. This is necessary due to the fact that
differencing VHD disks cannot be resized.

The procedure described above is applied during image spawn, resize and
live migration as needed.

Trying to spawn an instance with a local root disk size smaller than the
image VHD max. internal size will result in an error.

Change-Id: I04f18f0e25c92ed1e1f9f6f18750329a3f9f1711
Imporove db.sqlalchemy.api._validate_unique_server_name method

This method is called by instance_create and instance_update.
If parameter CONF.osapi_compute_unqiue_server_name_scope is set to
'global' or 'project' then it has terrible performance.

Algorithm was next:
1) Get all instances and all connected data (5 joinloads..) in global
   (or project).
2) Compare hostname with hostnames in instances (locally)

Now:
1) Get only count of instances with same hostname in global (or project).
2) If count > 0 raise Exception.

Change-Id: I35ea121c3f906b4fff11c38bafa2ab33200bd6b2
Rename source_(group_id/ip_prefix) to remote_(group_id/ip_prefix)

Fixes bug 1144426

Change-Id: I28735aea05738487861e477aaa3b0a3cec081821
Moves Hyper-V options to the hyperv section

Fixes Bug: 1140778

Due to the large number of options available in Nova, in order to
achieve better option organization and naming (e.g. avoid the hyperv_*
prefix) and to avoid option name clashes, options specific to the
Hyper-V driver are moved to a section named "hyperv".

Backwards compatibility is mantained by providing the "deprecated_group"
argument in option definitions.

For case consistency the group name as been changed to "hyperv" for options
introduced in Grizzly belonging to the group "HYPERV"

Change-Id: If2710822cdf6e4ae108a6d1e7977735ac8104a2e
Merge "Imporove db.sqlalchemy.api._validate_unique_server_name method"
Merge "Fixes disk size issue during image boot on Hyper-V"
Merge "Moves Hyper-V options to the hyperv section"
Merge "Rename source_(group_id/ip_prefix) to remote_(group_id/ip_prefix)"