fix include path
report errors with module loading to user
compression schemes for exr files
change default compression for exr to PIZ
change include path

This commit undoes the change introduced in cd3137edf1975e1feb0ec3f719b4db4808dafd2e

From ktd3rd:

The reason I got rid of the aces/ part of that is so that local cmake compiles where I don't do an install but use the cmake config mechanism to find my compiled folder, the header file is not yet placed in the install location (aces/), and is just in the local folder. So I made the installed rules include flags such that the include path is added "-I<prefix>/aces", such that #include <aces_Writer.h> works, which matches what the include flags are for OpenEXR (i.e. with the -I) when installed.
fixes to make unit tests pass