Add functional error tests for Delete Multiple Objects
Add functional error tests for Delete Multiple Objects

This patch adds functional error tests for Delete
Multiple Objects.

Add following error tests.
note: Object or Key tag is an element of request xml
- with invalid AWS secret key
- with bucket does not exist in Swift
- without object tag
- without value of Key tag
- specified number of objects is over CONF.max_multi_delete_objects
- specified xml size is over 61365 bytes

Change-Id: I172fcbde7a8da8f2809980f5e041c4954b48b301

swiftstack/swift3-stackforge,swiftstack/swift3-stackforge,tumf/swift3,KoreaCloudObjectStorage/swift3,KoreaCloudObjectStorage/swift3,stackforge/swift3,tumf/swift3,stackforge/swift3