Alert the user when using unsuported rails versions

Fixes #16

Author: xredo

pathfinder.rb

@@ -70,7 +70,7 @@ def call
 
        append_file 'Gemfile', "ruby \'#{utils.ask_with_default('Which version of ruby do you want to use?', default: RUBY_VERSION)}\'"
 
-       gem 'rails', utils.ask_with_default('Which version of rails do you want to use?', default: '4.2.5')
+       gem 'rails', Rails.version
        # Model
        gem 'aasm'
        gem 'keynote'

template.rb

@@ -1,3 +1,9 @@
+if Rails.version[0].to_i >= 5
+  puts ''
+  puts "\e[31mPathfinder only works with Rails versions lower than 5.0.\e[0m"
+  exit
+end
+
 path = if File.exists? @rails_template
           File.dirname(@rails_template)
         else