Complete package.dtd, add source-mirrors and pkg-changelogs elements
Add a sample package metadata xml using package.dtd as schema
package.dtd: add enc attribute to <license>
Place <provided-mime> after <signatures> in package.dtd
Add EntropyRepository.getPackageXmlData() method to output xml package metadata
Fix element order in package.dtd, signatures must follow extra-downloads
Fix license element syntax in package.dtd