Addition of 'notContains' parameter

[paulosfjunior]

Added parameter 'notContains' to check if the file has not been downloaded from the cypress download repository. Checks if any files in downloads have part of the name passed as a parameter.

If 'contains' is also given, 'notContains' will be ignored.

The revised code just returns 'True' or 'False' unless an error occurs, in which case it returns a 'throw'.

Added some more validations of variables at the beginning for code execution.