Adding algorithm for implicit feedback data to ALS
Split HadoopRDD into one for general Hadoop datasets and one tailored to Hadoop files, which is a common case.

This is the first step to avoiding unnecessary Configuration broadcasts per HadoopRDD instantiation.
Add a cache for HadoopRDD metadata needed during computation.

Currently, the cache is in SparkHadoopUtils, since it's conveniently a member of the SparkEnv.
Move Configuration broadcasts to SparkContext.
Merge remote-tracking branch 'upstream/master' into implicit-als
Merge remote-tracking branch 'oldsparkme/hadoopRDD-broadcast-change' into hadoop-config-cache
SPARK-900 Use coarser grained naming for metrics
Merge HadoopDatasetRDD into HadoopRDD.
remedy the line-wrap while exceeding 100 chars
Update README
fixed a bug of using wildcard in quotes
ask ivy/sbt to check local maven repo under ~/.m2
SPARK-920 - JSON endpoint URI scheme part (spark://) duplicated
SPARK-921 - Add Application UI URL to ApplicationInfo Json output
Allow users to set the application name for Spark on Yarn
Add default value to usage statement
Merge pull request #28 from tgravescs/sparYarnAppName

Allow users to set the application name for Spark on Yarn
Merge pull request #25 from CruncherBigData/master

Update README: updated the link
Merge pull request #26 from Du-Li/master

fixed a wildcard bug in make-distribution.sh; ask sbt to check local
maven repo in project/SparkBuild.scala

(1) fixed a wildcard bug in make-distribution.sh:
with the wildcard * in quotes, this cp command failed. it worked after
moving the wildcard out quotes.

(2) ask sbt to check local maven repo in SparkBuild.scala:
To build Spark (0.9.0-SNAPSHOT) with the HEAD of mesos (0.15.0), I must
do "make maven-install" under mesos/build, which publishes the java .jar
file under ~/.m2. However, when building Spark (after pointing mesos to
version 0.15.0), sbt uses ivy which by default only checks ~/.ivy2. This
change is to tell sbt to also check ~/.m2.
Merge remote-tracking branch 'upstream/master' into implicit-als