Update sinatra in Gemfile.lock

Keep up to date with required gems. Sinatra seems to have added in a new
header in responses.
Update cucumber in Gemfile.lock

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Update activesupport in Gemfile.lock

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Update fakefs in Gemfile.lock

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Update mustache in Gemfile.lock

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Update rake in Gemfile.lock

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Update webmock in Gemfile.lock

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Update nokogiri in Gemfile.lock

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Update rack-oauth2 in Gemfile.lock

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Update capybara in Gemfile.lock

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