Add explicit tar dependency for Augustus and Augustus Train

[pvanheus]

FOR CONTRIBUTOR:

• [x] - I have read the CONTRIBUTING.md document and this tool is appropriate for the tools-iuc repo.
• [x] - License permits unrestricted use (educational + commercial)
• [ ] - This PR adds a new tool or tool collection
• [x] - This PR updates an existing tool or tool collection
• [ ] - This PR does something else (explain below)

[pvanheus]

Both the Augustus and Augustus Train wrappers using tar with the -z option which is not supported in all versions of tar (e.g. the one in BusyBox doesn't support it). This PR adds an explicit dependency to resolve this issue.

[bernt-matthias]

Should tar be added to the conda recipe?