[MRG] Reduce file reads in handlers

[vinayak-mehta]

I got a 5 second improvement for a 100 page foo.pdf.

[codecov-io]

Codecov Report

Merging #89 into master will increase coverage by 0.01%.
The diff coverage is 90.9%.

@@            Coverage Diff            @@
##           master     #89      +/-   ##
=========================================
+ Coverage   87.69%   87.7%   +0.01%     
=========================================
  Files          13      13              
  Lines        1511    1513       +2     
  Branches      349     349              
=========================================
+ Hits         1325    1327       +2     
  Misses        129     129              
  Partials       57      57

Impacted Files	Coverage Δ
camelot/handlers.py	90.47% <90.9%> (+0.23%)	⬆️

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[bosd]

What is the status of this pr?
Can tests be triggered?