Move some configuration out of sqlite, remove disk access requirement, fix package installation bugs

[john-g-g]

Closes #97, closes #79, closes #78, closes #77

This commit addresses several installation bugs, in part by refactoring how the library defines its dependencies. It now uses the standard setup.py to define requirements, rendering many files in the package unnecessary. The refactoring also removes steemd url configuration data from sqlite, which improves installation errors that arise when install environment runtime disk write access is not desired.

[goldibex]

Thanks for this @john-g-g. Please do the following before review proceeds:

• The title of the PR should describe what the PR actually does.
• The first line of the description should be what is now the title. (please use the keyword closes, not fixes; this is just semantics but it's important that it all be the same)
• The rest of the description should, as briefly as possible, explain the changes introduced by the PR in plain English. In this case, where you're closing 4 issues on one PR, it should also explain why there is 1 PR for 4 issues rather than the conventional 1-to-1 relationship.

[cyon1c]

I'm going to close this @john-g-g because it's relatively outdated. The only thing I'm not clear on is the disk access requirement. If so, let's open an issue for it.