Ena-upload-cli

- Support for non mandatory columns in the viral sample table (Thanks tpall !)

- Better parsing of accession numbers and outputted in stdout in a tab separated manner
- Receipt is outputted as a receipt.xml file in the working directory
- Better handling of errors that do not produce a receipt
- Dropping support for python v2.X

- `--tool` option split in two: `--tool` TOOL_NAME default='ena-upload-cli' and `--tool_version` TOOL_VERSION default='0.2.5'
- `--tool` is not a mandatory option anymore
- tool_name and tool_version used for extra metadata fields in run, experiment, study and sample tables:

<RUN_ATTRIBUTES>
<RUN_ATTRIBUTE>
<TAG>SUBMISSION_TOOL</TAG>
<VALUE>${tool_name}</VALUE>
</RUN_ATTRIBUTE>
<RUN_ATTRIBUTE>
<TAG>SUBMISSION_TOOL_VERSION</TAG>
<VALUE>${tool_version}</VALUE>
</RUN_ATTRIBUTE>
</RUN_ATTRIBUTES>

- no support for password and webin-id as argument foor the tool anymore
- credentials are passed through .secret.yml file

- better password parsing from .secret file