WIP: Adds form types

[xavismeh]

This PR

1. intends to automatically create form types — one for Money\Money and an other one for a list of Money\Currency.
2. should not affect any user not using the form component.
3. should work out of the box if autowiring has been enabled

TODO:

• [x] add symfony receipe for flex (done: https://github.com/symfony/recipes-contrib/pull/831)
• [ ] add data transformer

[gmponos]

So this says WIP.. do we proceed here?

[xavismeh]

Will get back on this very soon !