Add Mode() to recorder

[Flamefork]

Fixes #48

[codecov-io]

Codecov Report

Merging #49 into master will increase coverage by 0.26%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #49      +/-   ##
==========================================
+ Coverage   76.87%   77.14%   +0.26%     
==========================================
  Files           4        4              
  Lines         173      175       +2     
==========================================
+ Hits          133      135       +2     
  Misses         25       25              
  Partials       15       15

Impacted Files	Coverage Δ
recorder/recorder.go	77.5% <100%> (+0.38%)	⬆️

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[dnaeon]

@Flamefork , thanks!