[SPARK-1945][MLLIB] Documentation Improvements for Spark 1.0

Standalone application examples are added to 'mllib-linear-methods.md' file written in Java.
This commit is related to the issue [Add full Java Examples in MLlib docs](https://issues.apache.org/jira/browse/SPARK-1945).
Also I changed the name of the sigmoid function from 'logit' to 'f'. This is because the logit function
is the inverse of sigmoid.

Thanks,
Michael
From my understanding the LabeledPoint instances consist of two fields:
a) The first field is the label of the point.
b) The second field is a double[] array (Vector[Double]) that consists of all the attributes' values.
I assume that I should switch the values in 'valuesAndPreds' variable so as prediction to proceed the actual label of each datapoint included in ths JavaRDD<double[]>.