よくあるエラー

Moped::Errors::OperationFailure: The operation: #<Moped::Protocol::Command
  @length=83
  @request_id=5
  @response_to=0
  @op_code=2004
  @flags=[]
  @full_collection_name="mongose_development.$cmd"
  @skip=0
  @limit=-1
  @selector={:getlasterror=>1, :w=>1}
  @fields=nil>
failed with error 13: "not authorized for insert on mongose_development.people"
See https://github.com/mongodb/mongo/blob/master/docs/errors.md
for details about this error.
  from /.rbenv/versions/2.1.4/lib/ruby/gems/2.1.0/bundler/gems/moped-10abbf3eac37/lib/moped/operation/read.rb:50:in `block in execute'
  from /.rbenv/versions/2.1.4/lib/ruby/gems/2.1.0/bundler/gems/moped-10abbf3eac37/lib/moped/node.rb:594:in `[]'
  from /.rbenv/versions/2.1.4/lib/ruby/gems/2.1.0/bundler/gems/moped-10abbf3eac37/lib/moped/node.rb:594:in `block (2 levels) in flush'
  from /.rbenv/versions/2.1.4/lib/ruby/gems/2.1.0/bundler/gems/moped-10abbf3eac37/lib/moped/node.rb:593:in `map'
  from /.rbenv/versions/2.1.4/lib/ruby/gems/2.1.0/bundler/gems/moped-10abbf3eac37/lib/moped/node.rb:593:in `block in flush'
  from /.rbenv/versions/2.1.4/lib/ruby/gems/2.1.0/bundler/gems/moped-10abbf3eac37/lib/moped/node.rb:617:in `block in logging'
  from /.rbenv/versions/2.1.4/lib/ruby/gems/2.1.0/gems/activesupport-4.2.0/lib/active_support/notifications.rb:164:in `block in instrument'
  from /.rbenv/versions/2.1.4/lib/ruby/gems/2.1.0/gems/activesupport-4.2.0/lib/active_support/notifications/instrumenter.rb:20:in `instrumen