Merged in pivot (pull request #1)

merge pivot to master
assembly
bigdf to dagorlad api - upload file

scala’ized Pinar’s uploader
updating .gitignore file
column strategy filter

zip only the subset of columns referenced in filter, calculate a
boolean vector, lazily use the vector to filter the columns in a newly
created DF.
compound predicates …TBD
compound predicates fixed

need to pass a map of column index to its position in the zipped rdds
toCSV, some refactoring, comments
rdd caching, aggregate improvements

- configurable storage level of rdd
- name the rdds so spark mgmt ui shows them in storage pane
- skip header for data is now optimized
- ignore leading/trailing whitespace in csv file fields
- guess column type based on first 5 (hopefully faster)
- uncache CSVRecords when done
- aggregate now returns a DF instead of RDD[k, v]
re-enable parse doubles UT, df.colNames
Merge branch 'master' of ssh://bitbucket.org/ayasdi/bigdf
README.md edited online with Bitbucket
snapshot
Column  - removed the tpe member and instead created functions isDouble and isString
Replaced def's with val's in Column
Merge branch 'master' of ssh://bitbucket.org/ayasdi/bigdf
Merged types_fix into master
extract column zipping, keyBy refactor
refactor aggregator

- column strategy only
- unit tests pass
- move to new file where “built-in” aggregations will be put
Merge branch 'master' into aggregate - tests ok

Conflicts:
	src/main/scala/com/ayasdi/bigdf/Column.scala
	src/main/scala/com/ayasdi/bigdf/DF.scala
	src/test/scala/com/ayasdi/bigdf/DFTest.scala
test aggregate by multi-column key

TBD: why did k work before instead of k(j)?