When more than one directory for helpers is provided to a controller, it
should preserver the order of directories. Given 2 paths:

    MyController.helpers_paths = ["dir1/helpers", "dir2/helpers"]

helpers from dir1 should be loaded first. Before this commit, all
helpers were mixed and then sorted alphabetically, which essentially
would require to rename helpers to get desired order.

This is a problem especially for engines, where you would like to be
able to predict accurately which engine helpers will load first.

(closes #6496)

railites_order method, introduced in 40b19e06, had a bug that was causing
loading application instance twice in initializers if railties_order
already included application instance. So for example

    railties_order = [Foo::Engine, :main_app, Bar::Engine]

would result in such railties array:

    [MyApp::Application, Foo::Engine, MyAppApplication, Bar::Engine]

In order to fix it, we need to check for existence of application in
both railties_order and railties arrays.

* update rails versions
* remove outdated code snippets
* few more corrections

This options can be used to not escape the result by default.

Initially the guide suggests to install gems via "bundle install --without db" 
But tests for ActiveRecord need to install the gems in db group also, like mysql.
The patch clears the bundler options in ".bundle/config" and installs all the gems in Gemfile

Refactoring the truncate method to not do a sort-circuit return

Truncate now has the ability to receive a html option that allows it to call rails helpers.

This way if my text is long I don't have to do something like this:

.text
= truncate(@text, :length => 27)

 if @text.size >= 27
    = link_to "continue", notes_path, ....."")

This guide is currently a wip and pending reviews. [ci skip]

installs only the gems that are already in the gemfile

[ci skip]

[guides] Update rails on rack

[getting started] Update Setting the Application Home Page to show the generated get "welcome/index" route

This is fairly common in Rails applications and is requested a lot of the time on Stack Overflow and #rubyonrails

Reset postgreSQL search path in db:test:clone_structure.

Reorder deep_symbolize_keys methods

Remove prepared statement from system query in postgresql adapter