added test for user following permission

This is a test case that allow a user to add another user to his followers by making a request

POST:/users/exampledoctor/following/users/examplepatient

The case is actually a patient want to share his activities with a doctor. A doctor cannot follow a patient but a patient can allow a doctor to see his data. Forum link for discussion 
https://groups.google.com/forum/?fromgroups=#!topic/usergrid/loATkUlv3uE