build(cloud9): remove ikpdb for python3 (no build)

cloud9/Dockerfile

@@ -15,7 +15,7 @@ RUN apt-get install -y \
 RUN curl -sL https://deb.nodesource.com/setup_6.x | bash -
 RUN apt-get install -y nodejs python python3 python-virtualenv python-dev python3-dev python-pip python3-pip tmux
 RUN pip install ikpdb bottle pyyaml pillow
-RUN pip3 install ikpdb bottle pyyaml pillow
+RUN pip3 install bottle pyyaml pillow
 
 # Install c9 SDK
 RUN git clone git://github.com/c9/core.git c9sdk; cd /c9sdk; git checkout master