Add development Dockerfile

[DomGarguilo]

This PR adds a development dockerfile and corresponding instructions to the readme.

This dockerfile and readme section were mostly copied from the accumulo-website dockerfile and readme.

[ctubbsii]

You said "mostly" copied from the Accumulo website README. More of it could be copied from that. They were originally much more identical, but diverged as Accumulo stopped using the staging site, and Fluo continued to use it. Fluo does not need to continue to use the staging site. We can build it directly from the commits to the main branch like we do for Accumulo's website.

[DomGarguilo]

Fluo does not need to continue to use the staging site. We can build it directly from the commits to the main branch like we do for Accumulo's website.

Should we open a ticket for this?

[ctubbsii]

Fluo does not need to continue to use the staging site. We can build it directly from the commits to the main branch like we do for Accumulo's website.

Should we open a ticket for this?

Just changing it in a PR would be fine.