feature request: enforce JavaDoc or ScalaDoc indentation

[ceedubs]

The official indentation recommendation for ScalaDoc is:

/**
  * Does stuff.
  */

However, many projects have adopted the JavaDoc-style indentation:

/**
 * Does stuff.
 */

It would be nice to be able to add a scalastyle rule to enforce one or the other (in my case I'm interested in enforcing consistent JavaDoc-style indentation).

Note: #188 mentions that IndentationChecker#isTabAlligned enforces the JavaDoc-style. However, I would be interested in a less restrictive rule that only applies to comments, as isTabAligned doesn't play nicely with some styles of code formatting that I tend to like.

[matthewfarwell]

I think that would be a good option. A PR would be wonderful.