Merge branch 'es_requirements' into 'master'

Update ES requirement

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/1254
Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/1251

See merge request !896

doc/integration/elasticsearch.md

@@ -31,7 +31,7 @@ is installed or on a separate server.
 These are the minimum requirements needed for Elasticsearch to work:
 
 - GitLab 8.4+
-- Elasticsearch 2.4+ (with [Delete By Query Plugin](https://www.elastic.co/guide/en/elasticsearch/plugins/2.4/plugins-delete-by-query.html) installed)
+- Elasticsearch 2.4.x (with [Delete By Query Plugin](https://www.elastic.co/guide/en/elasticsearch/plugins/2.4/plugins-delete-by-query.html) installed)
 
 ## Install Elasticsearch
 

lib/tasks/gitlab/check.rake

@@ -1007,15 +1007,14 @@ namespace :gitlab do
     client = Elasticsearch::Client.new(host: ApplicationSetting.current.elasticsearch_host,
                                        port: ApplicationSetting.current.elasticsearch_port)
 
-    print "Elasticsearch version >= 2.4? ... "
+    print "Elasticsearch version 2.4.x? ... "
 
-    version = client.info["version"]["number"]
+    version = Gitlab::VersionInfo.parse(client.info["version"]["number"])
 
-    # The version is greater or equal to 2.4.0
-    if Gitlab::VersionInfo.parse(version) >= Gitlab::VersionInfo.new(2, 4, 0)
+    if version.major == 2 && version.minor == 4
       puts "yes (#{version})".color(:green)
     else
-      puts "no".color(:red)
+      puts "no, you have #{version}".color(:red)
     end
 
     print "Elasticsearch has plugin delete-by-query installed? ... "