New rexray install image to support driver reinstallation and version update

[kaustavb12]

Implemented the rexray related TODO points mentioned in the stack file:

# 2. TODO: would prefer on-failure restart_policy, but need to run this in script to look
# for if plugin exists first before reinstalling

Changed restart_policy to on-failure. New script detects if plugin already installed and reinstalls if given version is different from installed version or does nothing if version matches. This behavior can be tweaked using script options.

# 3. TODO: would prefer this picks a driver version, and support driver updates

Specific driver version given for script to install. Can rerun script providing different version to update driver as required. Can also configure script options to reinstall using the 'latest' tag each time it runs.

Using rexray-plugin-installer project that I created. Below are the links:

GitHub:
https://github.com/kaustavb12/rexray-plugin-installer
Docker Hub:
https://hub.docker.com/r/kaustavb12/rexray-plugin-installer

[BretFisher]

Thanks for the tool and script @kaustavb12. I'm going to leave this PR here rather than merge for teaching reasons, rather than merging. Since this is a learning repo, I'm hesitant to add too much magic and would rather people see the "manual" way to do it, and then see this PR for an alternative approach.

Thanks again!