Update Hadoop 2.7 to 2.7.7

Author: srowen

assembly/README

@@ -9,4 +9,4 @@ This module is off by default. To activate it specify the profile in the command
 
 If you need to build an assembly for a different version of Hadoop the
 hadoop-version system property needs to be set as in this example:
-  -Dhadoop.version=2.7.3
+  -Dhadoop.version=2.7.7

docs/building-spark.md

@@ -67,7 +67,7 @@ Examples:
     ./build/mvn -Pyarn -DskipTests clean package
 
     # Apache Hadoop 2.7.X and later
-    ./build/mvn -Pyarn -Phadoop-2.7 -Dhadoop.version=2.7.3 -DskipTests clean package
+    ./build/mvn -Pyarn -Phadoop-2.7 -Dhadoop.version=2.7.7 -DskipTests clean package
 
 ## Building With Hive and JDBC Support
 

pom.xml

@@ -2681,7 +2681,7 @@
     <profile>
       <id>hadoop-2.7</id>
       <properties>
-        <hadoop.version>2.7.3</hadoop.version>
+        <hadoop.version>2.7.7</hadoop.version>
         <curator.version>2.7.1</curator.version>
       </properties>
     </profile>