Update README.md

Add web ui addresses and tutorial links
Update README.md
Update README.md
Create example.sbt

example of sbt configuration file used for building a standalone application
Update example.sbt
Create SparkPi.scala

example for standalone program
Create README.md

Instructions on how to run the program as an standalone application
Update README.md
Update README.md
Update README.md
add spark_join testing codes