bootstrap: Add feature to support extra data sets when app launch

bootstrap: Add feature to support extra data sets when app launch

User may want to set various data set for launching app.
after this implementation.
user can do like below

  - python
    extraData1 = LaunchData()
    extraData1.key = 'Key1'
    extraData1.value = 'Value1'
    extraData2 = LaunchData()
    extraData2.key = 'Key2'
    extraData2.value = 'Value2'

    datas = [extraData1, extraData2]
    stub.launchApp(ReqLaunchApp(packageName='org.tizen.example.NUITizenGallery', data=datas))

Change-Id: Id7756a080acb9e940d0679a4ae0ae89ccc9fb57e