Sevenbridges-python

- Improvements:
- Added bulk retrieval of tasks
- Added clone_direct app copy strategy
- Hide authentication token in debug level logs

- Fixed regression introduced by python 3.7 in which config parser does not allow for empty values

- Improvements:
- Added resource id type validation for get method to prevent invalid requests

- Updated travis configuration

- Improvements:
- Added app copy strategy parameter
- Added get_member methods on projects and volumes
- All resources now have a field() method for retrieving set values
- Allow greater dependency versions, only set minimum requirements
- Export and Import results now return entire file
- Update documentation

- Improvements:
- Added clone task endpoint