Encapsulated visual URL in new VisualUrl class.

Encapsulated visual URL in new VisualUrl class.

The VisualUrl object encapsulates the URL string and also resolves the data type
and whether the url is local or remote on creation.

Change-Id: I88cfc98563799d2646bde1911a5e8e90496ffd45
Signed-off-by: David Steele <david.steele@samsung.com>
Conflicts:
	automated-tests/src/dali-toolkit-internal/CMakeLists.txt
	automated-tests/src/dali-toolkit/utc-Dali-PushButton.cpp
	dali-toolkit/internal/file.list
	dali-toolkit/internal/visuals/animated-image/animated-image-visual.cpp
	dali-toolkit/internal/visuals/animated-image/animated-image-visual.h
	dali-toolkit/internal/visuals/image/image-visual.cpp
	dali-toolkit/internal/visuals/image/image-visual.h
	dali-toolkit/internal/visuals/npatch/npatch-visual.cpp
	dali-toolkit/internal/visuals/npatch/npatch-visual.h
	dali-toolkit/internal/visuals/svg/svg-visual.cpp
	dali-toolkit/internal/visuals/svg/svg-visual.h
	dali-toolkit/internal/visuals/visual-factory-impl.cpp