Specify images extension

Author: Dimitar Tasev

setup.py

@@ -117,7 +117,7 @@ def run(self):
     name="mantidimaging",
     version="2.0.0",
     packages=find_packages(),
-    package_data={"mantidimaging.gui": ["ui/*.ui", "ui/images/*"]},
+    package_data={"mantidimaging.gui": ["ui/*.ui", "ui/images/*.png"]},
     entry_points={
         "console_scripts": ["mantidimaging-ipython = mantidimaging.ipython:main"],
         "gui_scripts": ["mantidimaging = mantidimaging.main:main"],