[SPARK-4793] [Deploy] ensure .jar at end of line

sometimes I switch between different version and do not want to rebuild spark, so I rename assembly.jar into .jar.bak, but still caught by `compute-classpath.sh`

Author: Daoyuan Wang <daoyuan.wang@intel.com>

Closes #3641 from adrian-wang/jar and squashes the following commits:

45cbfd0 [Daoyuan Wang] ensure .jar at end of line

bin/compute-classpath.sh

@@ -68,14 +68,14 @@ else
   assembly_folder="$ASSEMBLY_DIR"
 fi
 
-num_jars="$(ls "$assembly_folder" | grep "spark-assembly.*hadoop.*\.jar" | wc -l)"
+num_jars="$(ls "$assembly_folder" | grep "spark-assembly.*hadoop.*\.jar$" | wc -l)"
 if [ "$num_jars" -eq "0" ]; then
   echo "Failed to find Spark assembly in $assembly_folder"
   echo "You need to build Spark before running this program."
   exit 1
 fi
 if [ "$num_jars" -gt "1" ]; then
-  jars_list=$(ls "$assembly_folder" | grep "spark-assembly.*hadoop.*.jar")
+  jars_list=$(ls "$assembly_folder" | grep "spark-assembly.*hadoop.*.jar$")
   echo "Found multiple Spark assembly jars in $assembly_folder:"
   echo "$jars_list"
   echo "Please remove all but one jar."
@@ -108,7 +108,7 @@ else
   datanucleus_dir="$FWDIR"/lib_managed/jars
 fi
 
-datanucleus_jars="$(find "$datanucleus_dir" 2>/dev/null | grep "datanucleus-.*\\.jar")"
+datanucleus_jars="$(find "$datanucleus_dir" 2>/dev/null | grep "datanucleus-.*\\.jar$")"
 datanucleus_jars="$(echo "$datanucleus_jars" | tr "\n" : | sed s/:$//g)"
 
 if [ -n "$datanucleus_jars" ]; then