Create v0.5.1

What

This MR will be used to create asimov 0.5.1 which will be a bugfix release for the 0.5 series.

Who

This MR will be prepared by @daniel-williams

Why

This MR is required to prepare a release which fixes a handful of bugs in the codebase which are corrected by previous MRs listed below:

• LIGO!98
• LIGO!93
• LIGO!94
• LIGO!92
• LIGO!90