fix warnings and removed some asserts

* removed lastAttemptedSubTree variable in octree server since we aren't using it.
* changed a bunch of asserts to debug messages since they produce warnings on unix and because the warning messages are a more graceful failure.
* fixed ByteCountCoded<> which was using T when it should have used int
@ey6es - can you double check that this is correct?

The goal was to fix this warning:
```
/mnt/ebs1/jenkins/jobs/hifi-pull-request-ubuntu/workspace/interface/src/MetavoxelSystem.cpp:2062:42: warning: ‘lastIndex’ may be used uninitialized in this function [-Wuninitialized]
```

In looking through the code, it appears that it's not actually possible for lastIndex to be used on the first pass, since it's only used if alpha0 != alpha2 or alpha0 != alpha4 and on the first pass through the loop these are all set to the same value. So I believe my change will have no effect on the logic, but does silence the warning.