new tooldev Planemo usage feedback

from @tiagoantao on using Planemo

I had several problems. I still have to be quite frank. Note that some problems below are not documentation related:
- Understanding the correct workflow. When should I use test, when should I use shed_test?
- What are the parameters for testing? The documentation (which is just a pull of the --help output) is not very clear about that. Sometimes I did not know if I was testing all the tools in a directory if or a single tool (this was particularly bad when I started working on a fork of tools-iuc).
- The speed of shed_test (with all the overheads)
- The output of the tests. For example, some cases the XML files were not correct, no help there. Also the format of the output on HTML is not helpful.

Suggestions:
- Put some concrete examples of usage in the documentation. Examples with shed_test and test.
- Make suggestions on planemo workflows.
- Run planemo lint before testing (automatically). I spent hours testing things that I should have linted. While this was a mistake of mine, the tool could actually have made life easier here.
- Easier test output to interpret...