Update contributing and cran comments

CONTRIBUTING.md

@@ -3,22 +3,18 @@ How to contribute to DeltaRho / datadr
 
 Thank you for sharing your code with the DeltaRho project. We appreciate your contribution!
 
-## Join the developer mailing list
-
-If you're not already on the DeltaRho developers list, take a minute to join.  This is as easy as sending an email to tessera-dev+subscribe@googlegroups.com.
-It would be great if you'd introduce yourself to the group but it's not required. You can just let your code do the talking for you if you like.
-
 ## Check the issue tracker
 
 Before you write too much code, check the [open issues in the datadr issue tracker](https://github.com/delta-rho/datadr/issues?state=open)
 to see if someone else has already filed an issue related to your work or is already working on it. If not, go ahead and
 [open a new issue](https://github.com/delta-rho/datadr/issues/new).
 
-## Announce your work on the mailing list
+## Announce your ideas in our gitter dev chat room
 
-Shoot us a quick email on the mailing list letting us know what you're working on. There
-will likely be people on the list who can give you tips about where to find relevant
-source or alert you to other planned changes that might effect your work.
+Shoot us a quick note on [gitter chat](https://gitter.im/delta-rho/dev) letting
+us know what you're working on. There will likely be people on there who can give
+you tips about where to find relevant source or alert you to other planned
+changes that might effect your work.
 
 If the work you're proposing makes substantive changes to datadr, you may be asked to attach a design document
 to your issue in the issue tracker. This document should provide a high-level explanation of your design, clearly define the goal

cran-comments.md

@@ -1,3 +1,5 @@
+This version has a few stability updates but mostly addresses a compatibility issue with the latest version of data.table.
+
 ## Test environments
 
 * local OS X install, R 3.3.1
@@ -32,13 +34,10 @@ There were 2 NOTEs:
     Availability using Additional_repositories specification:
       Rhipe   yes   http://ml.stat.purdue.edu/packages
 
-    * checking package dependencies ... NOTE
-    Package suggested but not available for checking: 'Rhipe'
-
 All words are spelled correctly.
 
 The Rhipe R package is not required for any of the core functionality of datadr.  It is an optional back end for datadr functions that ties R to Hadoop.  Rhipe is a Linux-only R package available at http://ml.stat.purdue.edu/packages but since it has specific system-level dependencies (Hadoop, protocol buffers 2.5, etc.), we do not anticipate it being made easily available on CRAN.  Since Rhipe only enhances functionality of datadr when used against a large Hadoop cluster, while all the same functionality runs fine without Rhipe on a local workstation, we believe it is safe to ignore this note.
 
 ## Downstream dependencies
 
-There are currently no downstream dependencies for this package.
+I ran R CMD check on the only downstream dependency, trelliscope, and it passed.