Added 'path' support to LightCouch

Modified CouchDbProperties / CouchDbConfig / CouchDbClientBase to support the 'couchdb.path' property. This property allows the specification of a path; this path will be added after the port part of the uri.

e.g. :  http://hostname.com:8080/database

The path property is useful when LightCouch is used under a proxy servlet and the servlet is not registered under the root "/" path, but to some other path, like "/database". Consequently, LightCouch should send requests to "http://hostname.com:8080/database" instead of "http://hostname.com:8080".