Add single_version parameter to GitVersionCheckCJM

  Bump version of dist & GitVersionCheckCJM to 4.27

Changes

@@ -3,6 +3,10 @@ Revision history for Dist-Zilla-Plugins-CJM
 Note: the version number of a plugin is the version of the dist in
 which it was last changed.
 
+4.27   NOT
+	[GitVersionCheckCJM]
+	  - Add single_version parameter
+
 4.26   2014-12-13
 	- Don't use Moose::Autobox (GitHub#3: Thanks, Olivier Mengué)
 	  Dist::Zilla doesn't use it anymore, so it's an extra prerequisite.

dist.ini

@@ -6,7 +6,7 @@ author  = Christopher J. Madsen <perl@cjmweb.net>
 license = Perl_5
 copyright_holder = Christopher J. Madsen
 
-version = 4.26
+version = 4.27
 
 [FileFinder::Filter / :CheckRecommend]
 finder = :InstallModules

lib/Dist/Zilla/Plugin/GitVersionCheckCJM.pm

@@ -17,7 +17,7 @@ package Dist::Zilla::Plugin::GitVersionCheckCJM;
 # ABSTRACT: Ensure version numbers are up-to-date
 #---------------------------------------------------------------------
 
-our $VERSION = '4.26';
+our $VERSION = '4.27';
 # This file is part of {{$dist}} {{$dist_version}} ({{$date}})
 
 =head1 SYNOPSIS
@@ -51,8 +51,21 @@ This FileFinder provides the list of modules that will be checked.
 The default is C<:InstallModules>.  The C<finder> attribute may be
 listed any number of times.
 
+=attr single_version
+
+If set to a true value, all modules in the distribution must have
+the distribution's version.  The default is false, which allows
+unchanged modules to retain the version of the distribution in which
+they were last changed.
+
 =cut
 
+has single_version => (
+  is  => 'ro',
+  isa => 'Bool',
+  default => 0,
+);
+
 # RECOMMEND PREREQ: Git::Wrapper
 use Git::Wrapper ();            # AutoPrereqs skips this
 
@@ -130,6 +143,13 @@ sub munge_file
     return 1;
   }
 
+  # If all modules must have the same version,
+  # and the module version is less than the dist version, that's a problem:
+  if ($self->single_version and $version < $distver) {
+    $self->log("ERROR: $pmFile: $version needs to be updated");
+    return 1;
+  }
+
   # If the module hasn't been committed yet, it needs updating:
   #   (since it doesn't match the dist version)
   if ($modifiedRef->{$pmFile}) {