revert nexus-staging-maven-plugin version to 1.6.7

Author: igdianov

pom.xml

@@ -384,7 +384,7 @@
           <plugin>
             <groupId>org.sonatype.plugins</groupId>
             <artifactId>nexus-staging-maven-plugin</artifactId>
-            <version>1.6.13</version>
+            <version>1.6.7</version>
             <executions>
               <execution>
                 <id>default-deploy</id>