FEATURE: add cookie path support

[featheredtoast]

Adds cookie path support for sites hosting cookies on subfolder paths.

Without this, other set-cookie headers' paths may be unable to set paths.

[codecov-commenter]

Codecov Report

Merging #524 (75f0491) into master (3142a0d) will decrease coverage by 0.09%. The diff coverage is 100.00%.

:exclamation: Current head 75f0491 differs from pull request most recent head df90ede. Consider uploading reports for the commit df90ede to get more accurate results

@@            Coverage Diff             @@
##           master     #524      +/-   ##
==========================================
- Coverage   87.35%   87.26%   -0.10%     
==========================================
  Files          18       18              
  Lines        1281     1264      -17     
==========================================
- Hits         1119     1103      -16     
+ Misses        162      161       -1     

Impacted Files	Coverage Δ
lib/mini_profiler/client_settings.rb	94.11% <100.00%> (-0.09%)	:arrow_down:
lib/mini_profiler/config.rb	88.31% <100.00%> (+0.15%)	:arrow_up:
lib/mini_profiler/timer_struct/sql.rb	85.00% <0.00%> (-0.37%)	:arrow_down:
lib/mini_profiler/timer_struct/page.rb	88.52% <0.00%> (-0.37%)	:arrow_down:
lib/mini_profiler/profiling_methods.rb	69.87% <0.00%> (-0.24%)	:arrow_down:
lib/mini_profiler/profiler.rb	83.19% <0.00%> (-0.22%)	:arrow_down:
lib/mini_profiler/snapshots_transporter.rb	91.66% <0.00%> (-0.12%)	:arrow_down:
lib/mini_profiler/gc_profiler.rb	96.20% <0.00%> (-0.05%)	:arrow_down:
lib/mini_profiler/timer_struct/request.rb	98.98% <0.00%> (-0.02%)	:arrow_down:
... and 1 more

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[SamSaffron]

looks good, we can nuke the .dup calls later.