Update the linkify regex

Update the linkify regex to support links with dashes and port numbers.
Merge pull request #110 from fede1024/linkify_regex_update

Expand the linkify regex to accept dashes and port numbers

The previous regex wasn't able to recognize URLs with dashes and port numbers. It was also considering string such as "foo.bar" as links. Both problems are now fixed, but this requires http/https to be present at the beginning of the URL.