[CDE-311] MimeType resolver does not handle .svg files, thus sending an ...

...unknown Content-type in the response header

	- [cpf-pentaho5] new MimeTypeHandler calls platform's org.pentaho.platform.util.web.MimeHelper, defaulting to cpf-core's pt.webdetails.cpf.utils.MimeTypes (if first one is not able to resolve)
	- added unit tests
	- added missing log4j.xml to /test-src (fixes unit test logging)