#23 Hard-coded dependency to SOJO

[The light in the dark]

The current implementation has a hard dependency to SOJO, that makes using the library with only JSON-LIB unachievable.
The offending class is the JsonView (DOH!), that creates an instance of the SojoJsonStringWriter, that depends on the net.sf.sojo.common.WalkerInterceptor, which is not even part of the sojo-optional, but the sojo core.

SOJO is not found in any maven repository, and it would be nice to be able to use it with JSON-Lib alone.