Implement disposition element parser

Implement disposition element parser

[Issue#] N/A
[Problem] N/A
[Cause] N/A
[Solution] Implement disposition element parser
disposition element is sub-element of tizen:app-control.
element name : tizen:disposition
value :
  inline - application running with submode
  window - application running with normal state
example :
  <tizen:app-control>
    <tizen:src name="test.html"/>
    <tizen:operation name="http://tizen.org/appcontrol/operation/test"/>
    <tizen:disposition name="inline"/>
  </tizen:app-control>
dispostion element requires platform level
[SCMRequest] N/A

Change-Id: Ia957cd0f5921e3a3ab25eb6394395c00f951de82