When creating the build directory with cmake it would print warnings like:

CMake Warning (dev) at /usr/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:273 (message):
  The package name passed to `find_package_handle_standard_args` (ALEMBIC)
  does not match the name of the calling package (Alembic).  This can lead to
  problems in calling code that expects `find_package` result variables
  (e.g., `_FOUND`) to follow a certain pattern.

I looked at how we did it for other modules and made the package with these warnings adopt the same style.

I also removed the EMBREE_LIBRARY variable as it seems like it was not used.
For me this showed up as a semi warning as module as set to FOUND but the LIBRARY was set to NOT_FOUND.
This seems to have been an oversight as the embree library consists of may smaller libraries, and we correctly search for those.
(@Brecht Van Lommel (brecht) or is it possible to build embree as a big blob of a library?)

With this I also noticed that some modules state that they set and use the _LIBRARY variable but the do in fact not do this.
I removed these comments from those files.

I've tested these changes and I don't think it will break anything, but I will put this up to review to make sure.