ignore non-alpha search chars; accept multi terms

Building on the work of @voanhduy1512 in #2471, this patch to `brew cask search` makes two enhancements.
* all non-alphanumeric characters are ignored (not just hyphens).  This makes the following search work as the user might expect: `brew cask search 0xed`
* all terms on the CLI are accepted (instead of respecting only the first argument).  This makes the following search work as the user might expect: `brew cask search google chrome`.

If I get any +1's on this functionality, will add docs and tests to the PR.