Comply to OAuth2 Login identity provider platform terms

[MrOrz]

Facebook Platform Terms:

Platform Terms 4.b: Your privacy policy must comply with applicable law and regulations and must accurately and clearly explain what data you are Processing, how you are Processing it, the purposes for which you are Processing it, and how Users may request deletion of that data.

Thus we add the following info to our privacy term (四、隱私及個人資料):

• How we process the platform data
• How to request delete of platform data
  • actually in 一、5 we already said that collaborators can email us to modify their personal data. However since it is not a clear "deletion" step, let's clarify it again in 四、隱私及個人資料.

[coveralls]

Coverage remained the same at 75.261% when pulling ddd3b3d on privacy-update into 712af7c on master.