update riak build scripts to use a newer Ubuntu image

[MoralCode]

Per my comments on #117 this seems like it should be logged as a TODO for anyone who is planning to use this.

The current config uses an ubuntu 18 docker image and a libssl1.0.0 library that isnt available in later version - there may be other issues too, thats just the one that i noticed

[iakkus]

Have you tried checking whether the riak package actually works with the newer Ubuntu image?

[MoralCode]

not yet. Im almost certain it wont (if the only change you make is changing the docker image tag) because the libssl1.0.0 package also needs upgrading (its not available in later ubuntu versions, only newer versions are). I'm also not sure what else might need to be upgraded and i'd like to get myself a little more familiar with the codebase before making a major change like this.

I was largely just filing this issue to document it so that someone can tackle it in the future, especially if I don't get around to trying it this semester.

[MoralCode]

#117 (comment) seems to be cited in the README of the ansible scripts as a workaround for this - may be useful to anyone looking to integrate the fix into the install process itself