Add tests for cinder/api/urlmap.py

Add tests for unquoting and parsing functions in
TestParseFunction class
Add tests for Accept class methods:
 - TestAccept class - test cases for processing content types
 - TestUrlMapFactory - test cases for urlmap factory
Add tests for URLMap class methods except __call__ method in TestURLMap

Change-Id: I3f1aa527f49175d9fac6fbe7309383709c30c237
Fix error when QuotaUsage.updated_at is NULL

When QuotaUsage.updated_at is None, it will raise non-expected exception.
Just verify it.

Fix bug 1197259

Change-Id: I2b41d025f8cffa6c0b3f0153a5194d5e7b1a05df
Merge "Fix error when QuotaUsage.updated_at is NULL"
Merge "Add tests for cinder/api/urlmap.py"