Add build files and clang-format config to gitignore (#1076)

.gitignore

 *~
 *.o
 *.so
+*.lo
 *.cu_o
 *.ptx
 *_ptx.h
@@ -32,6 +33,7 @@ log.cite
 .Trashes
 ehthumbs.db
 Thumbs.db
+.clang-format
 
 #cmake
 /build*