Clean up some private ivars and methods and move them into their own header files

Classes/BITCrashManager.h

@@ -55,7 +55,6 @@ typedef enum BITCrashStatus {
   NSString *_feedbackRequestID;
   float _feedbackDelayInterval;
   
-  NSMutableString *_contentOfProperty;
   BITCrashStatus _serverResult;
   
   int _analyzerStarted;
@@ -109,8 +108,4 @@ typedef enum BITCrashStatus {
 // will return the timeinterval from startup to the crash in seconds, default is -1
 @property (nonatomic, readonly) NSTimeInterval timeintervalCrashInLastSessionOccured;
 
-- (id)initWithAppIdentifier:(NSString *)appIdentifier;
-
-- (void)startManager;
-
 @end