remove apt-get update from install script

[hunterakins]

Describe the problem

In my opinion apt-get update shouldn't be written into the bash install script for two reasons. The instructions on the hologram site to install the sdk use the command

curl -L hologram.io/python-install | bash
There's an issue on the raspbian where apt uses IPv6 and the raspbian mirrors don't like IPv6 so you have to add the option Acquire::forceIPv4=true to successfully grab updates. Therefore, this command will fail, and an inexperienced Linux user won't understand why the curl command fails. A more experienced user will use a command like
curl -L hologram.io/python-install > holo_install.sh
and then edit the file to include the option in the apt-get update and install commands.
Furthermore, if the install fails for some reason (for example, the pip that comes with Raspbian is pip 1.5.6, which is incompatible with python requests (a pip upgrade is necessary for a successful build)), then another call to the install bash script will update again, which is mildly irritating.

Expected behavior

A system update should be done separately from the installation of the SDK (typical protocol for package install on Linux distro is to first update, then install).

Actual behavior

As you've gathered, it's not really a bug I'm describing as much as feature request.

Steps to reproduce the behavior

System information

• Linux on raspberry pi