Simple cleanup on Spark's Scala code while testing core and yarn modules:
-) Remove some of unused imports as I found them
-) Remove ";" in the imports statements
-) Remove () at the end of method call like size that does not have size effect.
Merge pull request #178 from hsaputra/simplecleanupcode

Simple cleanup on Spark's Scala code

Simple cleanup on Spark's Scala code while testing some modules:
-) Remove some of unused imports as I found them
-) Remove ";" in the imports statements
-) Remove () at the end of method calls like size that does not have size effect.