Adding DateFormat and CoordFormat funcs to modify init args

[agorman]

Thanks for the great package! I'd like to add two new methods to help with output formatting.

[barasher]

Hi,
Great idea !
Thanks !

[barasher]

Everything seems fine :)

[codecov-commenter]

Codecov Report

Merging #60 (6b788e6) into master (70f0835) will increase coverage by 0.56%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #60      +/-   ##
==========================================
+ Coverage   79.71%   80.27%   +0.56%     
==========================================
  Files           2        2              
  Lines         281      289       +8     
==========================================
+ Hits          224      232       +8     
  Misses         40       40              
  Partials       17       17              

Impacted Files	Coverage Δ
exiftool.go	71.78% <100.00%> (+1.16%)	⬆️

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