add UriFilter to additional filters

[estraph]

This PR adds a filter for URI objects as inputs to commands. Ensures the URI is not empty and that it parses.

Usage example, taken from a command I wrote to wrap a HTTP API:

required do
  uri :endpoint, scheme: :https
  string :api_key, default: nil
end

Tests pass locally:

Raphs-MacBook-Pro:mutations raph$ git status
On branch raph/uri-filter
nothing to commit, working directory clean
Raphs-MacBook-Pro:mutations raph$ rake
Run options: --seed 36168

# Running tests:

...........................................................................................................................................................................................................................................

Finished tests in 0.069457s, 3383.3883 tests/s, 7285.0829 assertions/s.

235 tests, 506 assertions, 0 failures, 0 errors, 0 skips

[khun84]

@estraph The filter operation always starts from the HashFilter and from there it will filter the nested input. The results of the nested filter will always flow back to HashFilter.

What I can see is all basic filter like StringFilter, FloatFilter and etc always return Array<Object, Symbol> in #filter. Are you sure returning e.message here will be handled gracefully by the error handler?

I think you might see the issue if you write a rspec with a Mutation::Commands that will trigger error on this filter.