LIBRARIES:  Check downloaded file sha-1 hash before use

This closes #40, but requires every user to have shasum available. A future version
may want to use sha256 instead of sha1, however sha256 is not available by default
on all platforms. While not all download sites offer https connections, if one is
available it will used. Unfortunately, this commit causes a rebuild of all libraries
used as their build.sh.in files are modified.