janino-fragment should use DynamicImport not Require-Bundle

[diamondq]

The janino-fragment leverages Require-Bundle to force the Janino library to retrieve classes from the Logback libraries. However, Require-Bundle is rigid, in that it assumes that the only location for Logback classes is in the logback library.

Unfortunately, the PAX Logging team (which is one of the most used OSGi logging libraries) wrapped/embedded the logback libraries into their library. Therefore, the original logback JARs are not usually present in an OSGi environment.

By changing the Require-Bundle to a
DynamicImport-Package: ch.qos.logback.*
the code becomes more flexible as it won't care which bundle provides the packages.