Merge branch 'release/0.1.5' into develop
Fix the convenience API meta programming.

* MediaInfo.respond_to?
* StreamProxy.respond_to?
* Alias open() to open_file() as it clashes with a Kernel method
  (which is inherited privately into each class).
* Alias format to fmt for the same reason.
Bump to 0.1.6.
Merge branch 'release/0.1.6'