[SPARKR-146] Support read/save object files in SparkR.
Add @seealso in comments and extract some common code into a function.
Merge pull request #120 from sun-rui/objectFile

[SPARKR-146] Support read/save object files in SparkR.
Added Quick Start Guide
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' of https://github.com/cafreeman/SparkR-pkg