Update activesupport/lib/active_support/json/backends/okjson.rb

Okjson not parsing " ' " (single quote character). Writing a method and adding conditions for the same.
For example the following Json response will not be parsed properly : 
[{'key' : 'value'}]
but if the response uses double quotes(") instead of single quotes (') it will work properly.
This commit will also take care of responses returned with single quotes.