redundant member "activeNetwork" is removed.
resolves #220 resolves #216 resolves #210 
#220 -> registerUser function have one more parameter deviceId. This
parameter value is "ANDROID_ID". So that we can understand which device
is sending request easily. 
#216 -> test code is written for registration when user uninstall and
installs app. Take a look at the cases
ApplicationTester.testRegisterUserWithId()
#210 -> registation status to server is stored in a preference. If it is
not registered to server successfully, it tries to register again