asciinema 0.9.9

Simple formula for building asciinema 0.9.9 from source (as suggested in #26011).
Can a test be added to do something more substantial than e.g. `--version` or `--help`? See `cmake.rb` for an example of an application formula with a good test and `tinyxml2.rb` for an example of a library formula with a good test. Thanks!