Xcode warnings present

[jnigro]

Hi! When I started using Xcode 10, I took the opportunity to update my project to use your latest version of the SDK. However, some warnings have now appeared. Below I am including them and the code changes necessary to make them disappear:

In file FsprgEmbeddedStoreController.m, the following line, produces error: Macro expansion producing 'defined' has undefined behaviour:

#define RETRIEVE_SSL_CERTIFICATES defined(MAC_OS_X_VERSION_10_6) && MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_6

Fixed by changing code to:

#if defined(MAC_OS_X_VERSION_10_6) && MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_6
    #define RETRIEVE_SSL_CERTIFICATES 1
#else
    #define RETRIEVE_SSL_CERTIFICATES 0
#endif

In class FsprgOrder, selector orderFromData, variable declaration errorDesc produces warning: Unused variable 'errorDesc'. It can be fixed by moving it inside the #if-then section, from:

NSString *errorDesc = nil;

#if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_6
    

to

#if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_6
    NSString *errorDesc = nil;

I would appreciate if you could incorporate these changes, so my code can be in sync with your repository. Thanks!