Use the push:bump-only task

Currently whenEnd of output from running `grunt bump-only -v`

````sh
Registering "grunt-push-release" local Npm module tasks.
Reading /Users/johnnyt/p/mediaforge/phoenix/node_modules/grunt-push-release/package.json...OK
Parsing /Users/johnnyt/p/mediaforge/phoenix/node_modules/grunt-push-release/package.json...OK
Loading "push-release.js" tasks...OK
+ bump-only, push, push-commit, push-publish, push-release
Reading package.json...OK
Parsing package.json...OK
Initializing config...OK
Loading "Gruntfile.coffee" tasks...OK
+ build, clean_symlinks, default, foo, lint, release, server, test

Running tasks: bump-only

Running "bump-only" task
Warning: Task "bump::bump-only" not found. Use --force to continue.

Aborted due to warnings.
````