Add better error messaging when FlowDef is null.
Merge pull request #254 from azymnis/argyris/null_flowdef

Add better error messaging when FlowDef is null.
Removed type paramater from RichPipe's using method and added it to to nested foreach method, which is only place where it appears to be used
Factored out handling of Context objects into new class SideEffectBaseOpertion. Added support for using Context to GroupBuilder, with mapStream the only currently supported method
SideEffectBaseOperation should be abstract
Merge pull request #257 from tresata/feat-context

Change type paramatrization of RichPipe.using and provide context for GroupBuilder
removed implicit conversions of java iterators and iterables to their scala counterparts
Adds a weighted PageRank example using Matrix API

Using the Matrix API only, runs a weighted or
unweighted PageRank algorithm. This functions in
a similar way to the existing weighted PageRank
example. See the inline Scaladoc for more details.
Merge pull request #259 from tresata/feat-javaconversions

Removed implicit conversions of java iterators and iterables to their scala counterparts
remove unused HLLInstance import
Merge pull request #261 from asiegel34/remove-HLLInstance-import

remove unused HLLInstance import
Merge pull request #256 from joshdevins/matrix-api-weighted-pagerank

Adds a weighted PageRank example using Matrix API
Add a partition method to RichPipe.
Rough outline of a partition job test.
Fix partition test.
Change partition to take a generic function from A->R, not just a predicate function.
Field -> Fields
Add arity match assert and discard tmp fields.
Fix PartitionJob test by specifying the order of the output fields.
Merge pull request #246 from arkajit/partition

Create a Partition method for RichPipe.