[Create, Delete functions] implements create and delete function for all elements

simple_example.py

 from nanospace import Nanospace
 
-usr = 'lucien'
-pw = 'coucou'
-srvAddr = 'http://localhost:8888/'
+usr = 'usrLogin'
+pw = 'usrPw'
+srvAddr = 'yourSrvUrl/'
 
 nanospace = Nanospace(srvAddr, usr, pw)
 print(nanospace.get_string_value(83))