Mark custom properties in image schema as non-base

Currently it is impossible to determine if given image schema property
is base or custom one and knowledge of that can be handy in some
situations.    Proposed change appends to every custom property special
key which determiness that it is not a base property.

Change-Id: I49255255df311036d516768afc55475c1f9aad47
Partial-Bug: #1371559
Fix bad header bug in glance-replicator

When trying to use "glance-replicator livecopy" to replicate the
images from one OpenStack glance to another, it encounters "Bad
header" error for "x-image-meta-virtual-size" header. This is
because this header is not in the whitelist of v1 API headers of
form "x-image-meta-xxx".

Another problem after adding this "x-image-meta-virtual-size" to
header whitelist is that the sqlalchemy fail due to virual_size is
"None", which cannot be converted to int. To fix this problem, we
should avoid converting the None value attribute in GET
/v1/images/detail response to the header of POST /v1/images. I
added the None value check, following what the way in
glance/common/utils.py image_meta_to_http_headers() method.

Closes-Bug: #1373333

Change-Id: I13182c4e3212024a9d5663cefd2951c576961f4f
Merge "Mark custom properties in image schema as non-base"
Merge "Fix bad header bug in glance-replicator"