At the end of All Packages page, give script to check all md5sums [trac #1120]

[bradfa]

Rather than have people want to check each package's md5sum by itself, which is annoying, so no one's going to do it, we should create a file holding all of the file names and md5sums so that it can be passed to md5sum using the "-c" switch to compare each listed file automatically. This way people are more likely to check the files as it's quick and easy.

Generating this should be simple, the md5sums themselves can be referenced as they are variables. The file name downloaded could be made a variable, too.

This is trac ticket: https://trac.clfs.org/ticket/1120