Clarify each argument in each line, two lines limit and add invocation style guide

[HyukjinKwon]

This PR clarifies each argument in each line, two lines limit and adds invocation style guide in "Spacing and Indentation".

[HyukjinKwon]

Hi @rxin and @jkbradley. I intendedly didn't add examples when it fits in two lines, for example:

foo(
  someVeryLongFieldName, andAnotherVeryLongFieldName, "this is a string", 3.1415)

because I actually see many variants, for example:

foo(someVeryLongFieldName, andAnotherVeryLongFieldName,
  "this is a string", 3.1415)

within Spark and started to worry if we should force it. Please let me know if we should add this too, or if I missed the intention in #58.

[jkbradley]

Not sure. I was taught this by @mengxr and have tried to enforce it in MLlib. Maybe other parts of Spark differ.

[HyukjinKwon]

@rxin, WDYT about this?

[rxin]

Thanks - merging.

You don't know Chinese, do you ? :p

[rxin]

cc @Hawstein do you have time to submit a patch to reflect this update?

[Hawstein]

@rxin Of course, will do it today when I have time.