Update versions to .pre

Author: estolfo

elasticsearch-model/lib/elasticsearch/model/version.rb

@@ -1,5 +1,5 @@
 module Elasticsearch
   module Model
-    VERSION = "6.0.0"
+    VERSION = '6.0.0.pre'
   end
 end

elasticsearch-persistence/elasticsearch-persistence.gemspec

@@ -24,7 +24,7 @@ Gem::Specification.new do |s|
   s.required_ruby_version = ">= 1.9.3"
 
   s.add_dependency "elasticsearch",       '~> 6'
-  s.add_dependency "elasticsearch-model", '~> 6'
+  s.add_dependency "elasticsearch-model", '>= 5'
   s.add_dependency "activesupport",       '> 4'
   s.add_dependency "activemodel",         '> 4'
   s.add_dependency "hashie"

elasticsearch-persistence/lib/elasticsearch/persistence/version.rb

@@ -1,5 +1,5 @@
 module Elasticsearch
   module Persistence
-    VERSION = '6.0.0'
+    VERSION = '6.0.0.pre'
   end
 end

elasticsearch-rails/lib/elasticsearch/rails/version.rb

@@ -1,5 +1,5 @@
 module Elasticsearch
   module Rails
-    VERSION = "6.0.0"
+    VERSION = '6.0.0.pre'
   end
 end