Support for picture-urls::(original) and profile picture

- fetch picture-urls::(original) field instead of picture-url
- use the first image of pictureUrls array as profile image
- update README to reflect these changes

Author: EppO

README.md

@@ -60,7 +60,7 @@ provider :linkedin, ENV['LINKEDIN_KEY'], ENV['LINKEDIN_SECRET'], :scope => 'r_fu
 When specifying which permissions you want to users to grant to your application, you will probably want to specify the array of fields that you want returned in the omniauth hash. The list of default fields is as follows:
 
 ```ruby
-['id', 'email-address', 'first-name', 'last-name', 'headline', 'location', 'industry', 'picture-url', 'public-profile-url']
+['id', 'email-address', 'first-name', 'last-name', 'headline', 'location', 'industry', 'picture-urls::(original)', 'public-profile-url']
 ```
 
 Here's an example of a possible configuration where the fields returned from the API are: id, email-address, first-name and last-name.

lib/omniauth/strategies/linkedin.rb

@@ -15,7 +15,7 @@ class LinkedIn < OmniAuth::Strategies::OAuth2
       }
 
       option :scope, 'r_basicprofile r_emailaddress'
-      option :fields, ['id', 'email-address', 'first-name', 'last-name', 'headline', 'location', 'industry', 'picture-url', 'public-profile-url']
+      option :fields, ['id', 'email-address', 'first-name', 'last-name', 'headline', 'location', 'industry', 'picture-urls::(original)', 'public-profile-url']
 
       # These are called after authentication has succeeded. If
       # possible, you should try to set the UID without making
@@ -33,7 +33,7 @@ class LinkedIn < OmniAuth::Strategies::OAuth2
           :last_name => raw_info['lastName'],
           :location => raw_info['location'],
           :description => raw_info['headline'],
-          :image => raw_info['pictureUrl'],
+          :image => raw_info.fetch('pictureUrls', {}).fetch('values', []).first,
           :urls => {
             'public_profile' => raw_info['publicProfileUrl']
           }