Fixed Crash when launching from background while audio playing; Ability to manage Sample Rate

My fork contains 2 changes:

1) Fixed issue https://github.com/alexbw/novocaine/issues/15#issuecomment-14393246
2) Now you can manage these variables:
#define sampleRateT  8000.0
#define IOBufferDuration 0.0232*2
look at this file https://github.com/soulfly/novocaine/blob/master/Novocaine/Novocaine.m
I think custom sample rate in your origin repo isn't working, i tried to set something other that 44100, but always 44100 i saw in log.
So, please review this issue and add to origin repo if you accept it.

Thanks