Update realdebrid.py

Code :
- Modification of 'get_all_hosters()' to do it faster
- Cleaning code
- Replace 'print' output by 'common.addon.log_debug'
- Optimize get_all_hosters() to make first and last domain OK.

Tested :
- send a youwatch link => it don't try to resolve ==> OK
- send a purevid => it try => resolved => OK
- send a mixture => it try => resolved => OK
- check the domain list returned to detect bad entry => seems OK with modifications of first and last entry (implemented in this version of realdebrid.py)