Added currency methods + properties

[oxy-coach]

Добавлено:

• поддержка методов /reference/currencies, /reference/currencies/create, /reference/currencies/{id}/edit
• поле currency в модели Order, DeliveryType, Site, Loyalty

[codecov-commenter]

Codecov Report

Merging #174 (0c96b25) into master (bb5a205) will increase coverage by 0.08%. The diff coverage is 96.29%.

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@@             Coverage Diff              @@
##             master     #174      +/-   ##
============================================
+ Coverage     83.68%   83.76%   +0.08%     
- Complexity     1100     1105       +5     
============================================
  Files           167      168       +1     
  Lines          4167     4194      +27     
============================================
+ Hits           3487     3513      +26     
- Misses          680      681       +1     

Files Changed	Coverage Δ
...del/Request/References/CurrenciesCreateRequest.php	66.66% <66.66%> (ø)
src/ResourceGroup/References.php	100.00% <100.00%> (ø)