BUG 2155 - depth parameter in URI

* added interface RestconfNormalizedNodeWriter
* added two implementations of RestconfNormalizedNodeWriter,
RestconfDelegatingNormalizedNodeWriter just calls normalized node
writer from yangtools and DepthAwareNormalizedNodeWriter is writer
implementation tha checks depth
* added CutDataToCorrectDepthTest (randomly failing, needs to be checked
or removed for now)
* added condition to xml and json normalized node writers to create
depth aware normalized node writer id depth is specified in writer parameters

Change-Id: I922942e24cbe505c2803644c25acd755fe4dfae7
Signed-off-by: Jozef Gloncak <jgloncak@cisco.com>
Signed-off-by: Jan Hajnar <jhajnar@cisco.com>
(cherry picked from commit f94de91bba1210fa852aaab0490743f9f3553e99)