libs: use nfs4j-0.17.8

Motivation:
bugfix and enhancements release:

Changelog for nfs4j-0.17.7..nfs4j-0.17.8
    * [8d349333] [maven-release-plugin] prepare for next development iteration
    * [2dde7fd4] nfs41: add device delete notification
    * [cac5cf5b] nfs41: fix layoutget usage with current stateid
    * [0fa114c9] [maven-release-plugin] prepare release nfs4j-0.17.8

Acked-by: Paul Millar
Target: master, 4.2
Require-book: no
Require-notes: no
(cherry picked from commit 72ef693)
Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>

pom.xml

@@ -742,7 +742,7 @@
         <dependency>
             <groupId>org.dcache</groupId>
             <artifactId>nfs4j-core</artifactId>
-            <version>0.17.7</version>
+            <version>0.17.8</version>
             <exclusions>
                 <exclusion>
                     <groupId>org.dcache.common</groupId>