Put all common functions into separate file gitflow-common.

Renamed shFlags.sh -> gitflow-shFlags
diff --git a/Makefile b/Makefile
index 11b0b9d..1da3fa1 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,8 @@
 SCRIPT_FILES+=git-flow-release
 SCRIPT_FILES+=git-flow-support
 SCRIPT_FILES+=git-flow-version
-SCRIPT_FILES+=shFlags.sh
+SCRIPT_FILES+=gitflow-common
+SCRIPT_FILES+=gitflow-shFlags
 
 all:
 	@echo "usage: make install"