Add SchemaContext to NormalizedNode parser in RESTCONF

Correct parsing of identities, instance-identifiers
and others, requires access to full SchemaContext,
not only subset of it.

Migrated to parser factory, which provides that
access in order to correctly deserialize
context-sensitive types.

Change-Id: Ic92b9ce745080076a10d654acaba39e5c59f2b42
Signed-off-by: Vaclav Demcak <vdemcak@cisco.com>