gitconfig: push.default, diff.tool

gitconfig

@@ -37,5 +37,11 @@
 [merge]
 	defaultToUpstream = true
 
+[push]
+	default = upstream
+
+[diff]
+	tool = vimdiff
+
 [alias]
 	short = log --graph --pretty=format:'%C(yellow)%h%Creset -%C(red)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit --date=relative --patience