Merge remote-tracking branch 'upstream/develop' into develop

* upstream/develop:
Don't use a bad 2.10 version
Alternate approach to wiring up the counters
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
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
Review comments
Move the UniqueID case class out of the Job class to avoid serializations of it grabbing a reference to its parent
Move the job conf variable name to be a constant in the Job object
Make the stats holders not need to be object globals
Resolve merge conflict
address PR comments
BDD DSL to test pipe transformations (adapted from https://github.com/galarragas/ScaldingUnit)
Merge branch 'develop' of github.com:twitter/scalding into develop

* 'develop' of github.com:twitter/scalding:
  "Require" sources in JobTests to have a mock buffer.
  Don't use a bad 2.10 version
  Fix typo
  Re-add mapValues to IdentityReduce
  make sure to push filterKeys mapside
  add filterKeys
  Add .filter to KeyedListLike