Custom scheme-cache-directory yang models are not replicated among

Custom scheme-cache-directory yang models are not replicated among
cluster members

The problem was talking about the MissingSchemaSources, where in
the master wasn't setup schema repo & schema registry correctly
based on the data from NetconfNode (from NetconfTopologySetup).
Espacially if the node was using the specific schema cache directory.
According to, slaves were trying to ask the master for sources
(YangTextSchemaSource). In this way, master was trying to resolve
sources from the empty schema repo and it was failing there.

JIRA: NETCONF-610
Change-Id: I84290c085b8a54a9758a85b68113c18aee284a1c
Signed-off-by: Jakub Toth <jtoth@luminanetworks.com>
(cherry picked from commit 7506ce46c6c1045d98fa3bef735e60649dabc009)