Add Syohei Yoshida's git-messenger package.

stsquad · stsquad · commit c9072e82047f · 2013-06-10T15:51:40.000+01:00
Currently the readme is a little spare as the package commentary is
empty. I'll submit a patch upstream for that.
diff --git a/recipes/git-messenger b/recipes/git-messenger
@@ -0,0 +1 @@
+(git-messenger :repo "syohex/emacs-git-messenger" :fetcher github)

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+(git-messenger :repo "syohex/emacs-git-messenger" :fetcher github)`