[SPARK-10421] [BUILD] Exclude curator artifacts from tachyon dependencies.

This avoids them being mistakenly pulled instead of the newer ones that
Spark actually uses. Spark only depends on these artifacts transitively,
so sometimes maven just decides to pick tachyon's version of the
dependency for whatever reason.

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #8577 from vanzin/SPARK-10421.

core/pom.xml

@@ -272,6 +272,14 @@
           <groupId>org.apache.hadoop</groupId>
           <artifactId>hadoop-client</artifactId>
         </exclusion>
+        <exclusion>
+          <groupId>org.apache.curator</groupId>
+          <artifactId>curator-client</artifactId>
+        </exclusion>
+        <exclusion>
+          <groupId>org.apache.curator</groupId>
+          <artifactId>curator-framework</artifactId>
+        </exclusion>
         <exclusion>
           <groupId>org.apache.curator</groupId>
           <artifactId>curator-recipes</artifactId>