Fix QuickStart example #1 warnings

[rcrews]

Warnings appear when running the sample code under QuickStart Guide to Using the AWS SDK for Ruby with warnings on:

#!/usr/bin/env/ruby -w
require 'aws-sdk-s3'  # v2: require 'aws-sdk'

s3 = Aws::S3::Resource.new(region: 'us-west-2')

s3.buckets.limit(50).each do |b|
  puts "#{b.name}"
end

The warnings are:

• aws-sdk-core-3.16.0/lib/aws-sdk-core/rest/request/endpoint.rb:52: warning: shadowing outer local variable - parts
• aws-sigv4-1.0.2/lib/aws-sigv4/signer.rb:441: warning: shadowing outer local variable - headers
• aws-sdk-core-3.16.0/lib/seahorse/model/shapes.rb:39: warning: instance variable @location not initialized

These updates silence the warnings.

[rcrews]

The TravisCI test failure is on JRuby 9.1.5.0 only. My changes pass on all other Rubies. I am not able to reproduce the error on JRuby 9.1.16.0. I wonder if the problem is with JRuby 9.1.5.0 (and has since been fixed in 9.1.16.0)? The error relates to calling [] on a nil object, but the spec says @location should default to nil, which is why I used nil for the initialization. The TravisCI problem is at aws-sdk-s3/lib/aws-sdk-s3/object_multipart_copier.rb#L56. The changes in commits 572052a and 9d0343a are not failing.

Robert

[rcrews]

I reverted the commit that initialized the location field. I'll work on solving the warning in another way.

[awood45]

Looks good, thanks!