Add docblock indent fixer

Ensure that docblocks for class methods and attributes are indented if present
EDIT: Ensure that any docblock uses the same indentation as the documented subject, regardless the type
Yes @stof, it one are using 5.5+ (and have it enabled), also I don't know how it works on HHVM.

It won't cost us anything, so... we could do it as well and please some more users.