chore: tell git that images are binary (#1082)

rix0rrr · web-flow · commit d7ef2a5245c0 · 2018-11-05T16:23:51.000+01:00
Stop git from transmorphing newlines in the .png and .jpg files that we
have now.
diff --git a/.gitattributes b/.gitattributes
@@ -7,3 +7,5 @@
 
 *.gif binary
 *.zip binary
+*.png binary
+*.jpg binary
