Rename coinKeeper -> bankKeeper

[ValarDragon]

Closes #2267

• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Updated relevant documentation (docs/)

• Added entries in PENDING.md with issue # - no changelog entry made since this was never exported, therefore breaks no API.

• rereviewed Files changed in the github PR explorer

---

For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #2273 into develop will not change coverage.
The diff coverage is 81.81%.

@@           Coverage Diff            @@
##           develop    #2273   +/-   ##
========================================
  Coverage    63.73%   63.73%           
========================================
  Files          140      140           
  Lines         8642     8642           
========================================
  Hits          5508     5508           
  Misses        2755     2755           
  Partials       379      379

[alessio]

Seems quite straightforward. ACK from me.

[cwgoes]

utACK, thanks @ValarDragon

Much less confusing now