Add .gitattributes file for language detection

.gitattributes

@@ -0,0 +1,15 @@
+# Documentation
+*.md          linguist-documentation
+docs/*        linguist-documentation
+
+# Licensing information
+COPYING       linguist-documentation
+LICENSE       linguist-documentation
+
+# Javadoc
+*.html        linguist-documentation
+*.css         linguist-documentation
+
+# Gradle configuration
+*.properties  linguist-configuration
+*.gradle      linguist-configuration