Add .gitattributes to make dist cleaner

Author: simPod

.gitattributes

@@ -0,0 +1,12 @@
+# Set the default behavior, in case people don't have core.autocrlf set.
+* text eol=lf
+/.gitattributes export-ignore
+/.gitignore export-ignore
+/.phpstorm.meta.php export-ignore
+/.scrutinizer.yml export-ignore
+/.travis.yml export-ignore
+/Makefile export-ignore
+/phpcs.xml.dist export-ignore
+/phpstan.neon.dist export-ignore
+/phpunit.xml.dist export-ignore
+/tests export-ignore