Correct uses of :params in docstrings

Replace all occurrences of :params with :param alongway
(matches http://sphinx-doc.org/domains.html#info-field-lists)

Change-Id: Ia01e563dd54cce1e763c076b15d1a47b790eb802
Change log from ERROR to WARNING when instance absent

Periodic task will update the host stat so that it will
collect all active instances and get their disk size
during the operation period, the instance might be resized
by nova operations, it will lead to disk file not exist
it's not an error from current design point of view, so
change from ERROR to WARNING to avoid confusion

Change-Id: I3b6f1416c248d9d4d2caaf2cc30a7c944685661c
Closes-Bug: #1243849
Rename instance_type to flavor in hyper-v virt driver

Renames 'instance_type' to 'flavor' in the hyper-v virt driver and
associated tests.

Part of blueprint flavor-instance-type-dedup

Change-Id: I769bf86a63283152c5bbc5644e7b74cc2bb24697
Merge "Correct uses of :params in docstrings"
Merge "Change log from ERROR to WARNING when instance absent"
Merge "Rename instance_type to flavor in hyper-v virt driver"