Update quota-set throw 500 error

The server doesn't check whether the parameter "quota_set" or
"quota_class_set" is in request
body.So the 500 error has been thrown.

We should catch the KeyError and transfer the KeyError to
400(HTTPBadRequest) instead of 500.

Closes-Bug: #1249971
(cherry picked from commit 2ed2f3aff8eee70e02eb995780af292057cfcad4)
Change-Id: I01260c77efa50324f3d203888689cdb1e94d2c21
Merge "Update quota-set throw 500 error" into stable/havana