Set more meaningful package version information in Manifest

Note that the current Specification-Version does not meet javadoc requirements: https://docs.oracle.com/javase/8/docs/api/java/lang/Package.html#getSpecificationVersion--

To be honest I'm not sure what these versions mean and what are they used for. Previously, they were used to build a Weld version info string used in a log message during init. This is not the case any more (most of the time we use a separate properties file).

See also:
https://docs.oracle.com/javase/tutorial/deployment/jar/packageman.html
https://docs.oracle.com/javase/8/docs/technotes/guides/versioning/spec/versioning2.html#wp89936