Add .filter to KeyedListLike
add filterKeys
make sure to push filterKeys mapside
Merge remote-tracking branch 'upstream/develop' into develop

* upstream/develop:
Re-add mapValues to IdentityReduce
Merge pull request #754 from twitter/mapValues-grouped

Re-add mapValues to IdentityReduce
Fix typo
Don't use a bad 2.10 version
Alternate approach to wiring up the counters
Merge pull request #748 from twitter/filterMethods

Add .filter to KeyedListLike
Fix typo
Move the keepAlive to the job class.

Remove the logger statements if flowProcess isn't defined. The sys.error in place means these statements will never be hit with a null.
First sketch at a sketch join
implicit evidence must come first
make some things private, avoid divide by zero in Sketched
Random needs seed
add some comments about maxReplicas math
"Require" sources in JobTests to have a mock buffer.

This is just adding an error message to inform users writing JobTests that they need to
provide buffers for every source used in the job.
Merge pull request #759 from daisyzhou/develop

"Require" sources in JobTests to have a mock buffer.
Merge pull request #756 from twitter/fix210ver

Don't use a bad 2.10 version