* treewide: http -> https sources
This updates the source urls of all top-level packages from http to
https where possible.
* buildtorrent: fix url and tab -> spaces
`cp`, `grep`, `chmod`, `sed` executables
no longer found when upgrading from nixos
15.09 to 16.03. Fixed by use of wrapper
script that brings these executables into
`PATH`.
Also fix lpd binaries on 64 bits machines
by use of `callPackage_i686`.