Let range accept integers

This fairly simple PR adds an interface convenience to `Worksheet.range`.  In master, range only accepts range strings like 'A1:C4'.  As a result, I regularly find myself doing things like ``ws.range(ws.get_addr_int(1, 1) + ':' + ws.get_addr_int(4, 3)``.  This PR just makes it so that `range` can accept integer sequences *in addition* to the current behavior.  So, e.g., I can just do ``ws.range((1,1,4,3))`` after this.

I could also change it to use ``*args`` instead, allowing either ``ws.range('A1:C4')`` or ``ws.range(1,1,4,3)``, but I wasn't sure if there's a preference against ``*args`` in `gspread`'s API or not.