[DX] Normalize generation tools
feature #286 [DX] Normalize generation tools (benji07)

This PR was merged into the 2.3.x-dev branch.

Discussion
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[DX] Normalize generation tools

Add an entity argument on the `doctrine:generate:crud` command

```
php app/console doctrine:generate:crud AcmeDemoBundle:Post
```

is equivalent to

```
php app/console doctrine:generate:crud --entity=AcmeDemoBundle:Post
```

Related to the issue #280

Commits
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6ebdfd4 [DX] Normalize generation tools