CMake - Option added to define the default toolkit resource path.

* Currently the resources folder is harcoded in compile time.
  This works on devices where applications are always installed
  in specific folders but doesn't work in other platforms like
  MS Windows where the user can install the application in any
  folder.

* An option has been added to the CMakeLists.txt file. By default
  the resource folder is hardcoded. This behaviour can be disabled
  by setting the option -DUSE_DEFAULT_RESOURCE_DIR=OFF and setting
  environment variables in installation time for DALI_IMAGE_DIR,
  DALI_SOUND_DIR, DALI_STYLE_DIR, DALI_STYLE_IMAGE_DIR and
  DALI_DATA_READ_ONLY_DIR.

Change-Id: I3eea313da150f577e25171f2d5fb4791209f5181
Signed-off-by: Victor Cebollada <v.cebollada@samsung.com>