Update ZippyshareCom.py

After the first update i reviewed the hole code and tested this smaller version. After 200 downloads i think this version could work. 

Worksummary:
- removed all unnecessary functions
- removed all unnecessary imports
- updated the get_download_url
   - found a second procedure the get the url
 
This is the first time I'm writing something like this, so I'd be happy about feedback