Hygiene: upgrade Gson to v2.4
Hygiene: upgrade Gson to v2.4

https://github.com/google/gson/blob/gson-2.4/CHANGELOG.md

Change-Id: I32f8f13984347b8e086cfe28a18912646257d86d

wikimedia/apps-android-wikipedia,anirudh24seven/apps-android-wikipedia,dbrant/apps-android-wikipedia,dbrant/apps-android-wikipedia,Wikinaut/wikipedia-app,Duct-and-rice/KrswtkhrWiki4Android,wikimedia/apps-android-wikipedia,dbrant/apps-android-wikipedia,anirudh24seven/apps-android-wikipedia,wikimedia/apps-android-wikipedia,Wikinaut/wikipedia-app,Duct-and-rice/KrswtkhrWiki4Android,carloshwa/apps-android-wikipedia,Wikinaut/wikipedia-app,carloshwa/apps-android-wikipedia,carloshwa/apps-android-wikipedia,dbrant/apps-android-wikipedia,carloshwa/apps-android-wikipedia,wikimedia/apps-android-wikipedia,anirudh24seven/apps-android-wikipedia,SAGROUP2/apps-android-wikipedia,Duct-and-rice/KrswtkhrWiki4Android,anirudh24seven/apps-android-wikipedia,Wikinaut/wikipedia-app,Duct-and-rice/KrswtkhrWiki4Android,dbrant/apps-android-wikipedia,carloshwa/apps-android-wikipedia,SAGROUP2/apps-android-wikipedia,Wikinaut/wikipedia-app,anirudh24seven/apps-android-wikipedia,SAGROUP2/apps-android-wikipedia,SAGROUP2/apps-android-wikipedia,Duct-and-rice/KrswtkhrWiki4Android,SAGROUP2/apps-android-wikipedia