More lenient YAML testing

Ruby before and after 2.0 formats YAML differently. This commit makes
a test more lenient of this difference so that CI builds on Ruby
2.2.2 pass.

[#93987158]

Author: Christopher Frost

lib/java_buildpack/util/configuration_utils.rb

@@ -65,8 +65,6 @@ def write(identifier, new_content, should_log = true)
 
             File.open(file, 'w') do |f|
               header.each { |line| f.write line }
-              # f.write(header.join('\n'))
-              # f.write('\n')
               YAML.dump(new_content, f)
             end
           else

spec/java_buildpack/util/configuration_utils_spec.rb

@@ -105,6 +105,7 @@ def file_contents(file)
     header = []
     File.open(file, 'r') do |f|
       f.each do |line|
+        break if line =~ /^---/
         header << line
       end
     end