Add StringFilter support for START_WITH and END_WITH operator

[napestershine]

Subject

Provides fix for:
#943 (comment)

I am targeting this branch, because its a new feature.

Provides fix for:
#943 (comment)

Changelog

### Added
- Add `StringFilter` support for `START_WITH` and `END_WITH` operator

[napestershine]

Can't fix Travis until other PR get merged. :(

[napestershine]

Can you please release this when it get merged. Thanks

[greg0ire]

Please format your commit message according to our rules :

• The commit message subject must be less than 50 characters and tell us what you did.
• The commit message body should tell us why you did it. It is optional but highly recommended.

Bad example :

Fixed bug #989 by removing call to defraculate()

Good example:

Remove call to defraculate()

Calling this function caused a bug because it interferes 
with calls to getSchmeckles().
Fixes #989

Also, please kindly squash your commits together. If you don't, we'll try to remember to do it for you but it's best if you save us this trouble.

How to do that?

1. git rebase -i origin/3.x, assuming origin is a git remote that points to this repository, and not your fork. If you're not sure what your remotes are, run git remote -vvv, there should be your fork and the holy/reference/base/origin/whatever-you-call-it repository.
2. A window will show up with many lines, replace pick with fixup on every line but the first one
3. Close your editor, git should do its magic, and you should end up with one commit
4. Use git push --force to overwrite what you already push. Don't forget the --force option otherwise git will try to merge both things together.

More details in CONTRIBUTING.md

[VincentLanglet]

Add StringFilter support for START_WITH and END_WITH operator

is a better commit name

[napestershine]

What else to do?

[VincentLanglet]

What else to do?

Waiting for the other PR to be merged and released

[VincentLanglet]

You need to change this line
https://github.com/sonata-project/SonataDoctrineORMAdminBundle/blob/3.x/composer.json#L30

To require

"sonata-project/admin-bundle": "^3.71",

[VincentLanglet]

Nice, it will be perfect if you squash your commit into a single one with a more explicit message like
"Add StringFilter support for START_WITH and END_WITH operator".

You also need to edit your first message to add the changelog message.
See your other PR for the format: sonata-project/SonataAdminBundle#6134 (comment)

[phansys]

Thank you @napestershine!

[napestershine]

Can you please release it. I need it in a project.

Thanks

[VincentLanglet]

@napestershine 3.20 is released.

[napestershine]

Thanks