Use Long instead of Int for numeric options

[JoshRosen]

We should use Long instead of Int for numeric options in order to support larger values (e.g. huge numbers of records), and verify that the data generators work for huge datasets.

The current code fails in the options parsing phase if it attempts to parse numbers bigger than IntMax:

Exception in thread "main" joptsimple.OptionArgumentConversionException: Cannot convert argument '4000000000' of option ['num-records'] to class java.lang.Integer
  at joptsimple.AbstractOptionSpec.convertWith(AbstractOptionSpec.java:94)
  at joptsimple.ArgumentAcceptingOptionSpec.convert(ArgumentAcceptingOptionSpec.java:276)
  at joptsimple.OptionSet.valuesOf(OptionSet.java:222)
  at joptsimple.OptionSet.valueOf(OptionSet.java:171)
  at joptsimple.OptionSet.valueOf(OptionSet.java:152)
  at spark.perf.KVDataTest.createInputData(KVDataTest.scala:62)
  at spark.perf.TestRunner$.main(TestRunner.scala:29)
  at spark.perf.TestRunner.main(TestRunner.scala)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:606)
  at org.apache.spark.deploy.SparkSubmit$.launch(SparkSubmit.scala:314)
  at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:73)
  at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
Caused by: joptsimple.internal.ReflectionException: java.lang.NumberFormatException: For input string: "4000000000"
  at joptsimple.internal.Reflection.reflectionException(Reflection.java:140)
  at joptsimple.internal.Reflection.invoke(Reflection.java:122)
  at joptsimple.internal.MethodInvokingValueConverter.convert(MethodInvokingValueConverter.java:48)
  at joptsimple.internal.Reflection.convertWith(Reflection.java:128)
  at joptsimple.AbstractOptionSpec.convertWith(AbstractOptionSpec.java:91)
  ... 14 more

[nchammas]

Partially resolved by #38.