[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
The only requirement for an inner class to call a variable declared in the outer class is by declaring the variable as final. I have fixed it! Thanks!