Added 3 Mac models to tested platforms list

All 3 models tested with Tails 1.1.2
Changed links to Tails v1.1.2 ISO and signature

1.1.1 was no longer available for download, which prompted the error message "ERROR! The iso does not seem to be signed by the TAILS key. Something is fishy!" to be displayed.

Changed links to get v1.1.2 and the script now works
Merge pull request #48 from Grezzo/master

Update to latest Tails version and add 3 Mac models to tested platforms list