Use AppBundle instead of AcmeDemoBundle
Other minor fixes
Use AppBundle instead of AcmeStoreBundle
Apply best practices to forms
Don't use form() helper
Minor tweak
Minor standard fix for best practices guide
Some fixes
feature #4507 Comply with best practices, Round 2 (WouterJ)

This PR was merged into the 2.3 branch.

Discussion
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Comply with best practices, Round 2

| Q   | A
| --- | ---
| Doc fix? | yes
| New docs? | no
| Applies to | all
| Fixed tickets | partly #4431

Less other fixes, more find/replace this time to speed up the process. I have one question this time:

* Should we just mention the use of the param converter (the current case), or update all simple controller examples to the use param converter?

Commits
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5ee9791 Some fixes
fdc460d Minor standard fix for best practices guide
2a97453 Minor tweak
a29f9fb Don't use form() helper
4ef1ef3 Apply best practices to forms
de4fcf4 Use AppBundle instead of AcmeStoreBundle
c8ce507 Other minor fixes
3c71b6d Use AppBundle instead of AcmeDemoBundle