#27 Avoid code repetition

[Pietro Zambelli]

Some functions are duplicate like: get_name_from_urn present in filters/GFfilter and in filters/GOfilter or the recently added function convertToSec present in: walib/istsos/services/procedures/procedures.py and in istsoslib/filters/RS_filter.py.

Perhaps you should consider to move these functions somewhere like: istsoslib/filters/utils.py or in istsoslib/utils.py