Add support for conditional fields

[almet]

I've opened a series of issues more to start a discussion about certain features than to tell it should be done. This is one of them and we need to decide if we want to have it or not.

[almet]

Conditional fields are sometimes useful, but seems to be technically complicated to do, especially with the use of JSON Schema. My personal belief is that we should avoid having them in the formbuilder unless we really need them.

[rlecellier]

Duplicated #133

[almet]

Nope, these two are different :-)

[DirtyF]

@almet : you mean you display a question for instance based on the previous answer?

[almet]

Yes, that's what I mean!

[almet]

I'm not sure we want this, unless we find a really easy way for the user to get over it.

[mehdisadeghi]

At least having children elements would be great. RJSF supports it out of the box, it's only a matter of passing the right schema to it.

[almet]

@mehdisadeghi please, if you have any idea on how to make this happen, send a pull request or mockups and we'll consider it.