Added userInfo and changed interface for request execution

[JFejza]

This is a convenience change on interface for request to enable configuration with userInfo dictionary
Issue: #3

[codecov-io]

Codecov Report

Merging #4 into master will increase coverage by <.01%.
The diff coverage is 71.42%.

@@            Coverage Diff             @@
##           master       #4      +/-   ##
==========================================
+ Coverage   90.14%   90.15%   +<.01%     
==========================================
  Files          31       31              
  Lines        2091     2103      +12     
==========================================
+ Hits         1885     1896      +11     
- Misses        206      207       +1

Impacted Files	Coverage Δ
VoxTests/DataSource/PaginationSpec.swift	82.41% <100%> (ø)	⬆️
...ox/Plugins/Alamofire/JSONAPIClient_Alamofire.swift	97.91% <100%> (ø)	⬆️
Vox/Core/Networking/Class/Request.swift	74.28% <50%> (-0.72%)	⬇️
VoxTests/DataSource/DataSourceSpec.swift	86.89% <70.58%> (+0.29%)	⬆️

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