Implement multiple file extensions for report type for reporter

ReportType class (https://github.com/arquillian/arquillian-recorder/blob/master/arquillian-recorder-reporter/arquillian-recorder-reporter-api/src/main/java/org/arquillian/recorder/reporter/ReportType.java) returns an string of extension report type (which in fact it is the extension of the file). There are some output formats which accepts different extensions, for example valid AsciiDoc extensions are ad, adoc or asciidoc.

So it would be a good approach to adapt the interface to allow the definition of multiple extensions.

Of course this generates a problem with which exporter to use in case of conflicts:

For example one can define:

html, html5
and
html, html4

and asks for html exporter. I think that in this case the first match should be returned.