Jupyterlab-code-formatter

**General**

- Minor updates to README - courtesy of akashlakhera and mzakariaCERN;

**Server extension**

No Change

**Jupyterlab extension**

- Remove some excessive logging - courtesy of jtpio;
- Make formatter commands visible for Python files and notebooks only - courtesy of jtpio;

**General**

- Add Binder to README - courtesy of jtpio;
- Add a test notebook for easier testing with Binder;

**Server extension**

- Add LICENSE in sdist - courtesy of xhochy;
- Handle the exsistence of magic commands in codecell for Black - courtesy of Lif3line;

**Jupyterlab extension**

No Change

- Handle format_str interface change for black>=19.3b0;
- Support Isort as a formatter;
- Bugfixes - courtesy of gnestor;

- Minor fix for formatting files in code cells;

- Support formatting files in FileEditor - courtesy of rbedi;

- Expose autopep8 options - courtesy of timlod;