Failed to import the compiled crcmod in GCE instance even after installation

Running into the same problem described in #176. My situation:

- Start a new Google Compute Engine instance with Ubuntu18.04 as the base image.
- Try to run `gsutil rsync` command and get the warning about slow pure python CRC implementation.
- Confirmed with `gsutil version -l` that compiled `crcmod` is not installed.
- Follow the instructions from `gsutil help crcmod` and install the compiled `crcmod` (and by the way, the installation instruction is wrong for ubuntu18.04. see detail below).
- Run `gsutil version -l` and `gsutil` still cannot find the compiled `crcmod`

The provided solution works and I noticed that the last reply said `gsutil 4.5` fixed this problem. But bundled the gcloud SDK installed in default image is 219.0.1 and the `gsutil 4.34` is shipped in the SDK.

If it is a problem with the gcloud SDK, please help forwarding to the SDK team.

For ubuntu 18.04 issue:

From [here](https://askubuntu.com/questions/1040392/easy-install-command-not-found):

> `easy_install` was removed from the `python-setuptools` package.

Use `sudo apt-get install python-pip` to install `pip` works for me as one the answers in that post suggested.