[SPARK-1636][MLLIB] Move main methods to examples

* `NaiveBayes` -> `SparseNaiveBayes`
* `KMeans` -> `DenseKMeans`
* `SVMWithSGD` and `LogisticRegerssionWithSGD` -> `BinaryClassification`
* `ALS` -> `MovieLensALS`
* `LinearRegressionWithSGD`, `LassoWithSGD`, and `RidgeRegressionWithSGD` -> `LinearRegression`
* `DecisionTree` -> `DecisionTreeRunner`

`scopt` is used for parsing command-line parameters. `scopt` has MIT license and it only depends on `scala-library`.

Example help message:

~~~
BinaryClassification: an example app for binary classification.
Usage: BinaryClassification [options] <input>

  --numIterations <value>
        number of iterations
  --stepSize <value>
        initial step size, default: 1.0
  --algorithm <value>
        algorithm (SVM,LR), default: LR
  --regType <value>
        regularization type (L1,L2), default: L2
  --regParam <value>
        regularization parameter, default: 0.1
  <input>
        input paths to labeled examples in LIBSVM format
~~~