yle-dl: install AdobeHDS.php, which is currently a dependency

Yle-dl currently [requires AdobeHDS.php](https://github.com/aajanki/yle-dl#installation) at least for downloading new TV programs. For example,

```
yle-dl http://areena.yle.fi/tv/2247816
```
fails with current yle-dl formula but succeeds after this commit. (Note that areena.yle.fi might be geoblocked.)

I had to make `AdobeHDS.php` executable to keep `brew audit` happy about non-executables, and change the test to allow a nonzero exit value (which `yle-dl --help` has given for some time).
Upstream fixed this by moving the php script to `/usr/local/share`: https://github.com/aajanki/yle-dl/commit/ad9ef7fa40b39ec315bb51fc509af7416278966c . I'll rewrite the pull request to accomodate later (I'm with relatives for the holidays...).

Should I make the AdobeHDS.php installation HEAD only for now, or should I patch the Makefile for older versions?