Unable to Deploy to Heroku

[BenMorganIO]

After setting up half pipe, I'm receiving this error when pushing to Heroku. I can't figure out what's happened hence the issue. I have also posted this on SO.

$ gph heroku master
Fetching repository, done.
Counting objects: 87, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (55/55), done.
Writing objects: 100% (68/68), 16.74 KiB | 0 bytes/s, done.
Total 68 (delta 24), reused 0 (delta 0)

-----> Removing .DS_Store files
-----> Ruby app detected
-----> Compiling Ruby/Rails
-----> Using Ruby version: ruby-2.1.1
-----> Installing dependencies using 1.5.2
       Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin -j4 --deployment
       Fetching gem metadata from https://rubygems.org/.........
       Fetching additional metadata from https://rubygems.org/..
       Fetching git://github.com/d-i/half-pipe.git
       Fetching git://github.com/joefiorini/sass-css-importer.git
       Using rake (10.3.1)
       Using i18n (0.6.9)
       Using json (1.8.1)
       Using minitest (5.3.3)
       Using thread_safe (0.3.3)
       Using builder (3.2.2)
       Using erubis (2.7.0)
       Using rack (1.5.2)
       Using mime-types (1.25.1)
       Using polyglot (0.3.4)
       Using arel (5.0.1.20140414130214)
       Using browser (0.4.1)
       Using addressable (2.3.6)
       Using referer-parser (0.2.1)
       Using geocoder (1.2.0)
       Using bcrypt (3.1.7)
       Using coffee-script-source (1.7.0)
       Using execjs (2.0.2)
       Using thor (0.19.1)
       Using daemons (1.1.9)
       Using orm_adapter (0.5.0)
       Using eventmachine (1.0.3)
       Using bundler (1.5.2)
       Using gravtastic (3.2.6)
       Using hike (1.2.3)
       Using multi_json (1.9.2)
       Using tilt (1.4.1)
       Using sass (3.2.19)
       Using mysql2 (0.3.15)
       Using request_store (1.0.5)
       Using rails_serve_static_assets (0.0.2)
       Using rdoc (4.1.1)
       Using rails_stdout_logging (0.0.3)
       Using tzinfo (1.1.0)
       Using warden (1.2.3)
       Using rack-test (0.6.2)
       Using treetop (1.4.15)
       Using coffee-script (2.2.0)
       Using uglifier (2.5.0)
       Using sprockets (2.11.0)
       Using thin (1.6.2)
       Using ahoy_matey (0.1.2)
       Using rails_12factor (0.0.2)
       Using activesupport (4.1.0)
       Using mail (2.5.4)
       Using sdoc (0.4.0)
       Using actionview (4.1.0)
       Using activemodel (4.1.0)
       Using intercom-rails (0.2.24)
       Using actionpack (4.1.0)
       Using jbuilder (2.0.6)
       Using rails-observers (0.1.2)
       Using actionmailer (4.1.0)
       Using activerecord (4.1.0)
       Using sprockets-rails (2.1.3)
       Using activeresource (4.0.0)
       Using railties (4.1.0)
       Using devise (3.2.4)
       Using wistia-api (0.2.3)
       Using jquery-rails (3.1.0)
       Using coffee-rails (4.0.1)
       Using sass-rails (4.0.3)
       Using rails (4.1.0)
       Using turbolinks (2.2.2)
       Using sass-css-importer (1.0.0.beta.0) from git://github.com/joefiorini/sass-css-importer.git (at load-paths)
       Using half-pipe (0.3.0.beta.2) from git://github.com/d-i/half-pipe.git (at master)
       Your bundle is complete!
       Gems in the groups development and test were not installed.
       It was installed into ./vendor/bundle
       Bundle completed (11.57s)
       Cleaning up the bundler cache.
-----> Preparing app for Rails asset pipeline
       Running: rake assets:precompile
       executing: "/tmp/build_b828be11-2086-4c4f-9fe7-0a30c7e6c833/node_modules/.bin/grunt build:public"
       rake aborted!
       Errno::ENOENT: No such file or directory - /tmp/build_b828be11-2086-4c4f-9fe7-0a30c7e6c833/node_modules/.bin/grunt
       /tmp/build_b828be11-2086-4c4f-9fe7-0a30c7e6c833/vendor/bundle/ruby/2.1.0/bundler/gems/half-pipe-8f75b3dcedd0/lib/tasks/assets.rake:16:in `exec'
       /tmp/build_b828be11-2086-4c4f-9fe7-0a30c7e6c833/vendor/bundle/ruby/2.1.0/bundler/gems/half-pipe-8f75b3dcedd0/lib/tasks/assets.rake:16:in `block (2 levels) in <top (required)>'
       /tmp/build_b828be11-2086-4c4f-9fe7-0a30c7e6c833/vendor/bundle/ruby/2.1.0/bundler/gems/half-pipe-8f75b3dcedd0/lib/tasks/assets.rake:37:in `block (3 levels) in <top (required)>'
       Tasks: TOP => half_pipe:execute_grunt_command
       (See full trace by running task with --trace)
 !
 !     Precompiling assets failed.
 !

 !     Push rejected, failed to compile Ruby app

[GeorgeStrakhov]

Just posted an ugly but workable solution here:
http://stackoverflow.com/a/26668172/1608883