V1.0.0 Release Requirements

[tempusfrangit]

For PGET to hit 1.0.0 release here is a rough list of what is required:

### 1.0.0 Release Requirments
- [x] Finalize abstractions
- [ ] https://github.com/replicate/pget/issues/37
- [ ] https://github.com/replicate/pget/issues/55
- [ ] Significantly improve testing coverage for critical path code
- [ ] Ensure documentation is updated/better
- [ ] https://github.com/replicate/pget/issues/61
- [ ] https://github.com/replicate/pget/issues/71
- [ ] https://github.com/replicate/pget/pull/119

[tempusfrangit]

1.0.0 is the milestone to where pget can be the default downloader for cog. Please feel free to suggest additional requirements.