form-group css class specific to vue-form-generator

[k8n]

... to avoid clashing with Bootstrap and others (#393)

• Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  bug fix

• What is the current behavior? (You can also link to an open issue here)
  form-group css class definition is greedy, clobbers Bootstrap's

• What is the new behavior (if this is a feature change)?
  form-group class definition on applies to children of vue-form-generator class

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
  Hopefully not

• Other information:

[zoul0813]

this should be a v3 fix, as it would introduce breaking changes to anything that uses VFG and may happen to inherit styles from VFG (intentionally or not) on the rest of the page.

I believe the best approach here is to provide a standard VFG CSS file, that isn't baked into the Vue components ... and then used Scoped CSS blocks within the components for any specific overrides or component only modifications.

@lionel-bijaoui - thoughts?

[ScopZy]

Not currently fixed ?