Reana-client

- Introduces user secrets management commands `secrets-add`,
`secrets-list` and `secrets-delete`.
- Enhances `run` and `create` commands to allow specifying
workfow via the `--workflow` flag.
- Introduces new command `version` to report client version.
- Fixes `upload` command behaviour for uploading very large files.
- Simplifies `run` command by removing free upload parameters.
- Upgrades `cwltool` to 1.0.20191022103248.
- Disables SSL verification warnings when talking to self-signed server
certificates.

- Introduces new `resources` field in `reana.yaml` specification file
allowing to declare computing resources needed for workflow runs, such as the
CVMFS repositories via `cvmfs` subfield.
- Improves `reana-client` embedded command-line documentation (`-help`) by
grouping commands and providing concrete usage examples for all commands.
- Enhances workflow `start` command allowing to override input parameters
(`--parameter`) and to specify additional operational options
(`--option`).
- Introduces new workflow `run` wrapper command that creates workflow, uploads
its input data and code and starts its execution.
- Introduces new workflow `stop` command for stopping a running workflow.
- Enhances workflow `logs` command output capabilities via new `--json`
option.
- Introduces new workflow `diff` command for comparing two workflow runs.
- Introduces new workflow `delete` command for deleting one or more workflow
runs.
- Introduces new session `open` command allowing to run interactive sessions
such as Jupyter notebook upon workflow workspace.
- Introduces new session `close` command for closing interactive sessions.
- Renames past `workflows` command to `list` allowing to list both workflow
runs and interactive sessions.
- Introduces new workspace `du` command for checking workspace disk usage.
- Introduces new workspace `mv` command for moving files within workspace.
- Introduces new workspace `rm` command for removing files within workspace.
- Renames past workspace `list` command to `ls` allowing to list workspace
files. Enhances its output capabilities via new `--format` option.
- Introduces new API function `create_workflow_from_json()` which allows
developers and third-party systems to create workflows directly from JSON
specification.

- Enhances test suite and increases code coverage.
- Changes license to MIT.

- Amends upload and download commands that will now upload/download all the
files specified in `reana.yaml` in case no arguments are provided.
- Fixes `status` command's JSON output mode.
- Upgrades CWL reference implementation to version `1.0.20180912090223`.
- Renames Serial workflow operational parameter from CACHING``to ``CACHE .
- Adds support for Python 3.7.

- Adds support for
[Serial workflows](http://reana-workflow-engine-serial.readthedocs.io/en/latest/).

- CLI refactored to a flat design:

- `inputs`/`outputs`/`code` removed, everything is a file managed
: with upload/download/list commands.
- Removes `workflow` command, workflows are managed with
: `create`/`start`/`status`.

- Removes `analyes` command, now `validate` is first level command.

- `status` now shows the selected workflow progress and current command on
verbose mode.

- Requires the usage of an access token to talk to REANA Server.

- Fixes bug when uploading binary files.

- Supports addition of workflow engine parameters when using `start` for
serial workflows.

- Improves error messages.

- Adds support for Common Workflow Language workflows.
- Adds support for persistent user-selected workflow names.
- Enables file and directory input uploading using absolute paths.
- Adds new `status` command to display the current status of the client.
- Reduces verbosity level for commands and improves error messages.