Divvy

Added
- adapters support, see [47](https://github.com/pepkit/divvy/issues/47) for detailed explanation
- `select_divvy_config` function
- `divvy submit` command
- added new `--compute` CLI argument
- `divvy write` can now be run without an outfile, which just prints the template to stdout.

Changed
- Instead of passing extra variables as CLI args, you now must explicitly pass them to the `--compute` arg.
- The config file is now passed with a positional argument, instead of with `--config`.
- Made all one-char CLI args lowercase (`-P` to `-p`, `-S` to `-s`).
- Renamed default templates subfolder from submit_templates to divvy_templates
- removed `$PEPENV` from environment variables that may point to divvy computing configuration file. `$DIVCFG` is the only one now.

Removed
- `config_file`, `no_env_error` and `no_compute_exception` from `ComputingConfiguration` class constructor

Fixed
- `NameError` in `divvy init`; [44](https://github.com/pepkit/divvy/issues/44)

Added
- possibility to execute library module as a script: `python -m divvy ...`

Changed
- improved error message when config format is incompatible

Added
- Default templates for singularity and docker compute packages
- `divvy init` function now initializes a default config setup.

Fixed
- `divvy` now shows help message with no args
- No longer print 'package activated' for default package

Changed
- Restructured the objects to use more `yacman` functionality under the hood.

Changed
- Removed utilities that are in `peppy`.
- Removed logging setup function.

Changed
- Fixed `divvy list` command

Changed
- Minor updates to improve interface with looper and peppy