[wrt][XWALK-1668]Add new audiopolicy testcase

Impacted TCs num(approved): New audiopolicy 7, update multiuser 3, deleted 0
Implacted TCs num(designed): New 2, Update 0, deleted 0
Unit test platform: [tizen]
UT result: Pass:7, Fail 1, block 1
Fail: Crosswalk_AudioPolicy_WebappAudioPlay: muti webapp audio is playing at the same time,does not meet the conflict policy
BugID:https://crosswalk-project.org/jira/browse/XWALK-2600
Block:Crosswalk_AudioPolicy_Muliple_Sinks: No bluetooth headset