Fix parse issue when genericClass of array is `NSURL`

[lanmaoxinqing]

fixed #190 问题根本原因在于，数组解析时，json 数据格式与目标模型格式不匹配

[codecov-io]

Codecov Report

Merging #281 into master will decrease coverage by 5.34%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #281      +/-   ##
==========================================
- Coverage   99.28%   93.93%   -5.35%     
==========================================
  Files           2        2              
  Lines        1540     1551      +11     
  Branches        0      427     +427     
==========================================
- Hits         1529     1457      -72     
+ Misses         11        7       -4     
- Partials        0       87      +87

Impacted Files	Coverage Δ
YYModel/NSObject+YYModel.m	93.33% <100%> (-5.89%)	:arrow_down:
YYModel/YYClassInfo.m	96.92% <0%> (-2.7%)	:arrow_down:

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