[Console] Allowing the user answering key or value of the autocompleterValues

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11116
| License       | MIT
| Doc PR        | ~

**Before**:
![capture d ecran 2014-12-05 a 01 07 54](https://cloud.githubusercontent.com/assets/667519/5308827/ebaec496-7c1b-11e4-8872-5ed1f3642836.png)

**After**:
![capture d ecran 2014-12-07 a 01 56 13](https://cloud.githubusercontent.com/assets/667519/5329554/493e8602-7db4-11e4-9667-ef4c8826317c.png)

NB: As we want the user to be able to type either "env_1" or "Launch this and that", I offered autocompletion too on the values of the autocompletedValues.

No, I take care about that in the method https://github.com/symfony/symfony/pull/12862/files#diff-c627c0171b08827e8021c93bbff5d10dR136