scm: mercurial: rewrite MercurialAdapter#entries to show per-file change log and size (#3421, #4455).

Contributed by Yuya Nishihara.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@4856 e93f8b46-1217-0410-a6f0-8f06a7374b81