Add GIFT-Grab compatible image renderer

[dzhoshkun]

• Can use the builder design pattern to separate the design from dependency.

• Can use PyGame.

The following are the core parameters of this renderer, related to GIFT-Grab video frames:

• color space
• dimensions

The following is a useful control parameter:

• frame rate

• The renderer should implement the GIFT-Grab observer interface

[dzhoshkun]

• add a simple demo application to verify the implementation

[dzhoshkun]

• remove sample app from Travis

[dzhoshkun]

• The following is the current state of the local copy:

diff --git a/vydemo/app/__init__.py b/vydemo/app/__init__.py
index adbc045..379ee3e 100644
--- a/vydemo/app/__init__.py
+++ b/vydemo/app/__init__.py
@@ -1,8 +1,27 @@
 import os.path
 from pkg_resources import resource_filename
+from vydemo.giftgrab import ColourSpace
 
 
 def let_the_sun_shine():
     filepath = resource_filename(__name__,
                                  os.path.join('data', 'sunny-river.mp4'))
     print('Let the sun shine on {}'.format(filepath))
+    video_reader = LocalVideoReader(filepath)
+    gui_director = GuiDirector()
+    gui_director.builder = PygameGuiBuilder()
+
+    gui_director.construct_gui(color=ColourSpace.BGRA,
+                               dims=(480, 720),
+                               frame_rate=10)
+    display = gui_director.builder.get_gui()
+
+    # configure processing pipeline
+    if display:
+        display.start()
+
+    while True:
+        image = video_reader.read()
+        display.update(image)
+
+    display.stop()

[dzhoshkun]

PyGame example that could be useful to what we're trying to achieve here.

[dzhoshkun]

Or maybe this file example.

[dzhoshkun]

• add usage info Add usage info to README #2
• add pygame to deps
• add note about OpenCV in demo