Allow logging individual check run times.

    pre-commit[josh/time_check_run_time]% PRE_COMMIT_DEBUG=true git commit -v
    PreCommit::Checks::Tabs 16.721ms
    PreCommit::Checks::NbSpace 0.17200000000000001ms
    PreCommit::Checks::Whitespace 6.819999999999999ms
    PreCommit::Checks::MergeConflict 9.574ms
    PreCommit::Checks::Debugger 10.395ms
    PreCommit::Checks::Pry 8.187ms
    PreCommit::Checks::Local 0.044ms
    PreCommit::Checks::Jshint 52.336ms
    PreCommit::Checks::ConsoleLog 0.033ms
    PreCommit::Checks::Migration 0.048ms
ahem :x