Updates:
- uses apache-airflow==1.10.12 & cwltool==3.0.20200710214758
- outputs CWL related logs into separate files
- supports simple scatter
- supports literal file inputs
Tested on [cwl-v1.1](https://github.com/common-workflow-language/cwl-v1.1/tree/be5ee84de20d41b6d7d94b3d2a71ddd591d1bf73) conformance test from Oct 7, 2020
- total: 253
- excluded: 2 (due to https://github.com/common-workflow-language/cwl-v1.2/issues/51)
- failed with known reason:
* 2 (due to https://github.com/common-workflow-language/cwl-v1.2/issues/52)
* 5 (due to https://github.com/Barski-lab/cwl-airflow/issues/43)
* 12 (due to https://github.com/Barski-lab/cwl-airflow/issues/44)
- success rate: 90%
*Reference: SDDA Sprint 1*