Added ability to customize query parameter names

[suth]

A problem mentioned in #31, #32, and #9 is that there is no way to change the parameter names used. Some developers customize the parameter names in spatie/laravel-query-builder or (like me) use spatie/laravel-json-api-paginate to match the JSON API spec.

I've written a new test and made a small attempt at an implementation. It might not be the best way to do this but since you asked for a PR I figured this would be a good start to get the feature rolling.

The main change is that a model can extend the parameterNames() method to change the parameters like so:

  parameterNames () {
    return {
      include: 'include_custom',
      filter: 'filter_custom',
      sort: 'sort_custom',
      fields: 'fields_custom',
      append: 'append_custom',
      page: 'page_custom',
      limit: 'limit_custom'
    }
  }

[codecov]

Codecov Report

Merging #42 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #42   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           4      4           
  Lines         233    237    +4     
  Branches       41     41           
=====================================
+ Hits          233    237    +4

Impacted Files	Coverage Δ
src/Parser.js	100% <100%> (ø)	⬆️
src/Model.js	100% <100%> (ø)	⬆️
src/Builder.js	100% <100%> (ø)	⬆️

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[robsontenorio]

Thanks, i will review it ASAP.

Can you update README with this new changes ?