Queue data for multiple requests while single mode launching

Queue data for multiple requests while single mode launching

- It launches only once for single mode. If another request comes while
it's running, store the next and show them in order. And returns all responses
when popup dies as it has been.

- If the number of requested popup exceed max popup number then ignore
new request. In normal situation, it will not exceed the max popup
number because the askuser throw exception for duplicated requests.

Change-Id: I8812a87d2dc691123bb82e04221109cb2074bf91
Signed-off-by: Yunjin Lee <yunjin-.lee@samsung.com>