Start 1.28.0 development cycle

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/Makefile b/Makefile
index d604a13..9c316e9 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 VERSION = 1
-PATCHLEVEL = 27
+PATCHLEVEL = 28
 SUBLEVEL = 0
-EXTRAVERSION =
+EXTRAVERSION = .git
 NAME = Unnamed
 
 # *DOCUMENTATION*