feature #728 Added a new AppBundle to comply with Symfony Best Practices (javiereguiluz)

This PR was squashed before being merged into the 3.0-dev branch (closes #728).

Discussion
----------

Added a new AppBundle to comply with Symfony Best Practices

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #671
| License       | MIT
| Doc PR        | -

Symfony Best Practices recommend to start developing your applications with a single AppBundle bundle. This PR allows to include that AppBundle in the Symfony Standard Edition, to make it easier for developers.

I used the same skeleton as for the `generate:bundle` command, but I thought that it would be better to simplify it and remove the `$name` route parameter and use just a static template without parameters.

Commits
-------

45da0d0 Added a new AppBundle to comply with Symfony Best Practices
Removing installation instructions

We have this multiple other places
minor #751 Removing installation instructions (weaverryan)

This PR was merged into the 2.3 branch.

Discussion
----------

Removing installation instructions

Hey guys!

We have the installation instructions in too many places. Ultimately, as we get the new symfony.com/download page and the downloader, this will reduce to just *one* spot (likely the download page, with a hand-off to continue by reading the docs).

On this repo, we should have no installation docs - it should just point to the central place. I also think we can just link to the current version of all of the docs for the bundle.

Thanks!

Commits
-------

22589ce Removing installation instructions
changed version to 2.3 in the README
[Tests] Ignored the Resources and Tests directories for the new AppBundle
bug #756 [Tests] Ignored the Resources and Tests directories for the new AppBundle (saro0h)

This PR was merged into the 2.3 branch.

Discussion
----------

[Tests] Ignored the Resources and Tests directories for the new AppBundle

Commits
-------

876ebcd [Tests] Ignored the Resources and Tests directories for the new AppBundle
Issue #758 Modified default route for AppBundle
bug #762 Issue #758 Modified default route for AppBundle (Pierstoval)

This PR was merged into the 2.3 branch.

Discussion
----------

Issue #758 Modified default route for AppBundle

Commits
-------

223e6c8 Issue #758 Modified default route for AppBundle