How To install npm, node, mocha, mongo

I wanted to install npm on my docker, but if exec-ing into it and doing a simple `apt-get update` it fails. Any idea how to provide the tools we need to use Bamboo properly?

```
apt-get update
E: Could not open lock file /var/lib/apt/lists/lock - open (13: Permission denied)
E: Unable to lock directory /var/lib/apt/lists/
E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?
daemon@bamboo-server-vpcfn:/var/atlassian/bamboo$ su root
su: must be run from a terminal
```

No repository file or test is named. Start by inspecting how the Docker image builds and how the Bamboo container is run, then reproduce the permission failure; done means the image or documented setup provides npm, Node, Mocha, and MongoDB without the shown apt or terminal errors.

Written by the indexing model from the issue text.