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* remove outdated code snippets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