Merge branch 'release/v0.1.0'

Update version in Project.toml

Fixes runtests.jl import name

Adds test train split + tests

Updates Project.toml and REQUIRE to include Statistics

Adds one hot encoder + tests

Updates README

Adds fill_missing_scalar + tests

Adds fill_missing function + tests

Adds docstring to standard_scaler

Adds standard_scaler + tests

Adds min_max_scaler + tests

Additional formatting of tests and project

Additional project set up

Create project structure