Streamlining user interface

[nsheff]

A collection of problems I ran into when trying to use looper for a project:

• [x] #459
• [x] it was too hard for me to create a project from a yaml table https://github.com/pepkit/peppy/issues/458
• [x] #460
• [x] #461
• [x] pep 2.1.0 docs were not the deployed docs
• [ ] #462

[nsheff]

example: I would like to make a peppy.Project from a sample yaml file:

- sample_name: sample 1
  file: path/to/file.tsv
- sample_name: sample 2
  file: path/to/2.tsv

prj = peppy.Project(sample_yaml="path.yaml")

or `prj = peppy.Project(sample_yaml={ ... sample dict ... })

[nsheff]

these are all done, or tracked in other issues.