Updates vmware-fusion6 checksum
The current checksum is not correct for some reason. I removed the .dmg managed
by homebrew-versions and ran `install --force` only to get another checksum
mismatch. I then downloaded the file directly from vmware.com and got the same
checksum that homebrew-version was getting but failing to match.
Merge pull request #504 from scottsuch/fix_vmware-fusion6_checksum

Updates vmware-fusion6 checksum