Add titles to middleware pages

[gmcgibbon]

Right now the pages you visit that route to the middleware don't have HTML titles or valid markup. This fixes that.

[codecov-commenter]

Codecov Report

Merging #552 (55e2a34) into master (edbcad3) will increase coverage by 0.78%.
The diff coverage is 100.00%.

❗ Current head 55e2a34 differs from pull request most recent head af5d27a. Consider uploading reports for the commit af5d27a to get more accurate results

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@@            Coverage Diff             @@
##           master     #552      +/-   ##
==========================================
+ Coverage   87.39%   88.17%   +0.78%     
==========================================
  Files          18       18              
  Lines        1269     1269              
==========================================
+ Hits         1109     1119      +10     
+ Misses        160      150      -10     

Impacted Files	Coverage Δ
lib/mini_profiler/profiler.rb	85.41% <100.00%> (+1.90%)	⬆️
lib/mini_profiler/client_settings.rb	95.58% <0.00%> (+1.47%)	⬆️

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[nateberkopec]

Rebase and LGTM 👍