Grand-challenge-forge

Stop using '/tmp' in example Dockerfiles to contain non-transient files.

Replace "input"/"output" in the context JSON input with "algorithm_input"/"algorithm_output".

* Various improvements to spelling and wording in the challenge packs
* Report grand-challenge-forge version in generated pack README
* Use challenge-level archives instead of phase-level archives for the pack README
* Add support for reading and writing TIFF files
* Disable network in test runs

* Various improvements to spelling and comments in the challenge packs
* Fixed passing `'is_image'`, `'is_json'` to the prediction.json example of the evaluation method
* Added a generic `read_file()` / `write_file()` to the evaluation.py and inference.py of the algorithm and evaluation examples, respectively

Adds challenge packs, consisting of:
* example upload algorithm
* example submission algorithm
* example evaluation method