Fixed an issue related to multiple database connection

Fixed an issue related to multiple database connection

- As every web application has its own security dao,
  support of multiple DB connections will not be needed.

[Issue#]   N/A
[Problem]  Setting menu shows wrong information with the following steps.
           1. Launch Setting -> Manage applications
           2. Select Web application -> Allow list
           3. Back to Manage applications -> select another Web application
           4. checking Allow list menu
           then, the menu showed the firstly chosen web application information.
[Cause]    Security origin dao is not released even though corresponding dao object is released.
           This causes returning old data when a new dao object is created.
           N.B) Security origin dao uses static value to avoid
                conflict with re-created connection object.
[Solution] Remove static dao value, and clen up old dao code.
           - We originally needed "static value" to support thread locking mechanism.
             But, current web applications don't have separate threads, hence no longer needed.
           - Moreover, sqlite already supports such a conflict through transaction manager.
[SCMRequest] N/A

Change-Id: Ide83f7c8fa63a387e48f0396c3a8febc79409101