MODE-1995 Fixed the initial content import of nodes defined in namespaces that do not have a http-like URI

The problem was caused by the fact that when parsing the XML, new nodes are created & stored in a path-keyed map, but the path itself isn't encoded. However, when attempting to persist the new nodes via a session, the unencoded path was encoded using a default encoder. This meant that parent-child relationships were not recognized correctly. 

In addition, another inconsistency was fixed: when importing nodes which have their name explicitly specified via `jcr:name` instead of using the preconfigured node type (on the importer) or `nt:unstructured`, the actual XML name of the element was being set as the node type. This behavior was completely inconsistent with the other nodes (which didn't have the `jcr:name` attribute) for which either the preconfigured node type property or `nt:unstructured` was used.