The application name is used to fill the `database.yml` and
`session_store.rb` files ; previously, if the provided name contained
whitespaces, it led to unexpected names in these files.

Since Shellwords.escape adds backslashes to escape spaces, the app_name
should remove them and replace any space with an underscore (just like
periods previously).

Also improve the assert_file helper to work with paths containing spaces
using String#shellescape.

This lets us avoid the constant calls to Array#<<

* master: (23 commits)
  Escape the parentheses in the default function regexp
  Update docs on Tilt::Template in Asset Pipeline guide
  Fix loading a sql structure file on postgres when the file's path has whitespace in it
  remove trailing whitespace added with b0577658 [ci skip].
  Allow unscope to work with `where.not`
  Raise an exception when model without primary key calls .find_with_ids
  Process sub-query relation's binding values
  Instrument the generation of Action Mailer messages
  Remove extra variable creation and merge.
  In Relation#empty? use #exists? instead of #count.
  [ci skip] avoid deprecation warning in sample code
  Convert Fixnum into String the port number in MySQL
  Fix some indentation on autosave association
  Make define_non_cyclic_method simpler
  Add Sass gobbling info to asset pipeline docs
  Ensure the state is clean after one failure
  Fix typo in form_helper.rb
  add a new local variable to track if digests are being stored, to ensure the cleanup works correctly
  [ci skip] Fix number of methods added by association.
  update digestor code based on review
  ...

Inline bind values for sub-queries generated for Relation in where

Conflicts:
	activerecord/CHANGELOG.md

This is causing every default value in PostreSQL database to being
handled as default function.

Fixes #12581

Fix loading a sql structure file on postgres when the file's path has whitespace in it

Update docs on Tilt::Template in Asset Pipeline guide

Allow unscope to work with `where.not`

Allows you to call #unscope on a relation with negative equality operators,
i.e. Arel::Nodes::NotIn and Arel::Nodes::NotEqual that have been generated
through the use of where.not.

Raise an exception when model without primary key calls .find_with_ids

Remove extra variable creation and merge.

Instrument the generation of Action Mailer messages

Generated sub-query for Relation as array condition for `where` method
did not take in account its bind values, in result generates invalid SQL query.

Fixed by adding sub-query relation's binding values to base relation

Closes: #12586

The processing of outbound mail is instrumented with the key
`process.action_mailer`. The payload includes the mailer name as well as
the mailer method.

In Relation#empty? use #exists? instead of #count.

avoid deprecation warning in sample code [ci skip]

Convert Fixnum into String the port number like `db:structure:dump` task in MySQL.

Account.find(1, lock: true)
-> DEPRECATION WARNING: Passing options to #find is deprecated. Please build a scope and then call #find on it.

Small cleanup on autosave association