Allow users to change default plugin parameters

[Edgard Marx]

One good enhancement of the framework will be allow users to change the default parameters of a plugin.

e.g. Sina plugin have default SPARQL endpoint as http://dbpedia.org, maybe users would like to change it for their own endopoint. This issue is even more useful if the engine is used over command line.

[Edgard Marx]

The version 0.62 already contemplate this really good enhancement,