Upgrade Gson to v2.6.2
Upgrade Gson to v2.6.2

https://github.com/google/gson/blob/master/CHANGELOG.md#version-262

Change-Id: I91b244c4f986d3cc20aece295fbc37204bf8b42d

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