updated .gitattributes to leave Brittany alone

And by Brittany I mean all image formats due to: [this](angular-fullstack/generator-angular-fullstack#1382)

Author: W3stside

.gitattributes

@@ -1,2 +1,8 @@
 # Set the default behavior, in case people don't have core.autocrlf set.
-* text eol=lf
+* text eol=lf
+
+# Denote all files that are truly binary and should not be modified.
+*.png binary
+*.gif binary
+*.jpg binary
+*.jpeg binary