bugfix: strip comments in drill/dig output when checking txt in dns.

The dns query is often being reprinted as a comment as part of the drill/dig output
this caused multiple hits for the grep, making the comparison invalid.
Make sure we strip out comments before we look for the challenge text in the txt record.

Add CHECK_PUBLIC_DNS_SERVER

Fixes for get_auth_dns

Improve test stability

Add tests for multiple ACL

Update version to 2.30

Fixes problems with SANS separated by spaces and commas (failed tests are DNS problems)

Fix slow fork bomb when directory containing getssl isn't writeable (…).  
_Note failed tests are just due to slow DNS propagation_

Change to use -sigalgs.  Fixes #570

getssl updets itself by:
- checking for a new version
- if so:
  - download the new one into a tmp location
  - rename the current one to name with version appended
  - rename the tmp file to the current location
  - run the new version
If the renaming fails, the old version gets run, which again downloads, etc.
Now exit if the rename (install command) fails.