Just noted that you can´t sign Android APKs with the Java 1.7 jarsigner. So I wonder why this is and what is the difference between the 1.6 and 1.7 signer?
Yes you CAN use 1.7!
It is very tricky to find info on the usage with 1.7, but once found it is reasonable simple:
For keytool include
-sigalg SHA1withDSA -keyalg DSA -keysize 1024
For jarsigner include
-sigalg SHA1withDSA -digestalg SHA1
(1024 is the maximum and works, less might do the trick)