Fixed the isLocal determination.

- check "mapreduce.framework.name" for YARN (hadoop 2.0)
- set both "mapred.job.tracker" and "mapreduce.framework.name" when setting the local bit
- converted all instances of handling "mapred.job.tracker" to use the proper handling
Merge pull request #1 from sjlee/sjlee-mapred-jobtracker-fix

Fixed the isLocal determination