Merge branch 'master' into devstein/changelog-0.15.0

RELEASING.md

@@ -1,6 +1,9 @@
 # How to release
 
-1. Update versions in all three `__init__.py` files.
-2. Merge `master` into `release`.
-3. Tag on `release`.
+1. Make sure `CHANGELOG.md` is up-to-date with all changes since last release.
+2. Update versions in all three sub-package's `__init__.py` files.
+3. Merge `master` into `release`.
+4. Create a new release on `release` branch with https://github.com/jupyter-incubator/sparkmagic/releases/new — make sure you do it on `release` branch, the default is `master`. Tag format is "0.15.0", no "v" prefix.
+
+[Possibly we should drop `release` branch concept, not sure it adds anything, and just do releases on `master`, but that's how it was when I got here. —Itamar]