second indexedrdd design
Finished early prototype of IndexedRDD
Adding testing code for indexedrdd
IndexedRDD passes all PairRDD Function tests
adding better error handling when indexing an RDD
changing caching behavior on indexedrdds
Merge branch 'master' of https://github.com/mesos/spark into indexed_rdd2
Merged with changes to zipPartitions
Corrected all indexed RDD tests.

There appears to be an issue with subtract by key tests that needs to be investigated further.
Merge branch 'master' of https://github.com/mesos/spark into indexed_rdd
Updating documentation.
Wrapping the index in an opaque type.
Allowing RDD to select its implementation of PairRDDFunctions
Merging upstream changes.
Fixing IndexedRDD unit tests.
Removing commented out test code
Mering changes from master
Merge branch 'indexed_rdd' of /Users/jegonzal/Documents/amplab/spark