Error reporting redundancy

[hansioan]

If the validation process produces no error, there is no point in returning a list of the form [None, None, None] One can just report an empty list. Additionally a list of the form: ['Error: the length of description is not right', None, 'Error: the description contains a tool name'] also contains redundancy, the None part is not needed. So one can just remove all the Nones from the error list and if there are no errors then the list would be empty.

@MigleSur the error: 'Error: the length of description is not right' can be more specific by mentioning whether the description is too long or too short.

[MigleSur]

I'm aware of this redundancy, working on fixing it. Updated the length function, so it reports if the description is too long/too short or it is made only from one word.