add basic log4j.xml for tests to avoid log4j warnings
reformat pom.xml
add bouncycastle pgp library
use entry type defined for this tag
add signing with PGPPrivateKey
implement PGP signature generator
add signature generation to Builder and test building RPM with and without signature
create rsa and pgp signature
Merge remote-tracking branch 'upstream/master'
Merge pull request #40 from ImmobilienScout24/master

Signing RPMs via Bouncy Castle Security Provider