Add Cask for LastPass Universal Mac OS X

This patch adds support for the LastPass Universal
Installer for Mac, which is a .dmg containing
all of the LastPass browser extensions.
Remove uninstall line in Lastpass Universal cask
Remove version number and SHA

Change to 'latest'
Set sha1 to 'no_checksum' for Lastpass Universal cask
Merge pull request #979 from kevinSuttle/lastpass-universal

Add Cask for LastPass Universal Mac OS X