Enforce image_size_cap on v2 upload

image_size_cap should be checked and enforced on upload

Enforcement is in two places:
- on image metadata save
- during image save to backend store

(cherry picked from commit 92ab00fca6926eaf3f7f92a955a5e07140063718)
Conflicts:
	glance/location.py
	glance/tests/functional/v2/test_images.py
	glance/tests/unit/test_store_image.py

Closes-Bug: 1315321
Change-Id: I45bfb360703617bc394e9e27fe17adf43b09c0e1
Co-Author: Manuel Desbonnet <manuel.desbonnet@hp.com>