remove tarballs from repo and distribution

[edwardhartnett]

Once #64 is working, remove the tarballs from the build.

Certainly we don't want large binary files in the repo, since these tarballs are readily available elsewhere.

We also do not want to install any libraries that are not present. By doing this, we are using old versions of the libraries, which have not been approved or installed by system admins.

For example, on all NOAA systems, there is a copy of netCDF, and it has been approved and installed (correctly) by the system administrators. Everyone needs to use that install of netCDF, no one should be installing their own copy of netCDF under any circumstances. If the system install of netCDF is not adequate (and we can check this in the cmake file), we stop the build and tell the user to get a proper netCDF install before trying again.

From the sysadmins point of view, they cannot have everyone installing their own copies of netCDF, it's wasteful and dangerous.

From the programming point of view, it makes debugging confusing, because the programmer assumes wgrib2 is using the system install of netCDF (like every other application does) and will not be aware that wgrib2 has its own copy of (a different version of) netCDF. Hilarious confusion may ensue.