Do not expect database user with app name to exist

By default when creating a project with `--database=postgresql` the `config/database.yml` file that is generated has a user specified that is the same as the app name

```
development:
  adapter: postgresql
  encoding: unicode
  database: <%= app_name %>_development
  pool: 5
  username: <%= app_name %>
  password:
```

This is counterintuitive and would rarely be valid. By default postgres creates a user with the current user name (http://www.postgresql.org/docs/9.3/static/database-roles.html) "it will have the same name as the operating system user that initialized the database cluster":

```
$ whoami
schneems
```

If the `username` is left out postgresql will assume that you wish to log in as the default user

```
$ psql -c '\du'
                             List of roles
 Role name |                   Attributes                   | Member of
-----------+------------------------------------------------+-----------
 schneems  | Superuser, Create role, Create DB, Replication | {}
```

A good sensible default then for auto generated `database.yml` files is to remove the `username`, and have postgres attempt to connect to the database as the currently logged in user.

Instead of submitting with a blank password, don't submit a password.
Merge pull request #13417 from TalkativeTree/comments_change

fix CollectionAssociation's comments
Use sass-rails 4.0.1
Merge pull request #13418 from ma2gedev/update_sass_rails_4_0_0

Use sass-rails 4.0.0
Merge pull request #13188 from imanel/skip_deep_munge

Add configuration option to optionally disable deep_munge

Conflicts:
	actionpack/CHANGELOG.md
Fix AS::NumberHelper results with large precisions

before:
  ActiveSupport::NumberHelper.number_to_rounded '3.14159', precision: 50
  => "3.14158999999999988261834005243144929409027099609375"
after:
  ActiveSupport::NumberHelper.number_to_rounded '3.14159', precision: 50
  => "3.14159000000000000000000000000000000000000000000000"
Merge pull request #13415 from schneems/schneems/database-no-username

Do not expect database user with app name to exist
Bump Jbuilder version to 2.0.0
Merge pull request #13422 from rwz/master

Bump Jbuilder version to 2.0.0
`html` and `text` templates for mailers by default
fix url connections for sqlite3
converts hashes in arrays of unfiltered params to unpermitted params [fixes #13382]
Merge pull request #13425 from kassio/master

Generates html and text templates for mailers by default.
Test with 2.1.0-rc1
refactors AC::Parameters#fetch

AC::Parameters#fetch was refactored in 7171111 to prevent self mutation, but
in doing so it hardcodes logic #convert_hashes_to_parameters is supposed to
encapsulate.

Better leave the delegation, and add a way to avoid mutating self in there.
Add a changelog entry for #13363 [ci skip]
optimizes array conversion in AC::Parameters
Add a changelog entry for #13326 [ci skip]
Fix typo [ci skip]
Fix few typos in the documentation [ci skip]