Release 4.7.0.

Squashed commit of the following:

commit ee3098aec81b64c9abe55626c6e8e6da930aa79c
Author: HARUYAMA Seigo <haruyama@unixuser.org>
Date:   Thu Feb 27 16:45:28 2014 +0900

    Add link(http://haruyama.blog.jp/archives/51922530.html).

commit 1b2a8abe5d85b338900352abed0bc8c660d6b775
Author: HARUYAMA Seigo <haruyama@unixuser.org>
Date:   Thu Feb 27 09:15:25 2014 +0900

    Fix package name.

commit 7013969685d430080834f6810b2ce9608c643774
Author: HARUYAMA Seigo <haruyama@unixuser.org>
Date:   Wed Feb 26 10:23:30 2014 +0900

    Use and modify Solr 4.7.0 code.