Cleanup RespokeCall.m
Cleanup RespokeCall.m

Document private class members.
Move private stats methods to appropriate #pragma declaration

iosyoujian/respoke-sdk-ios,i-miss-you/respoke-sdk-ios,Havi4/respoke-sdk-ios,i-miss-you/respoke-sdk-ios,Havi4/respoke-sdk-ios,i-miss-you/respoke-sdk-ios,JeeLiu/respoke-sdk-ios,respoke/respoke-sdk-ios,JeeLiu/respoke-sdk-ios,Havi4/respoke-sdk-ios,respoke/respoke-sdk-ios,iosyoujian/respoke-sdk-ios,iosyoujian/respoke-sdk-ios,respoke/respoke-sdk-ios,JeeLiu/respoke-sdk-ios