Was not building properly without libsodium installed
Merge pull request #241 from hintjens/master

Was not building properly without libsodium installed
Allow libsodium to be installed in a custom path
Solaris/SmartOS fix for libsodium
Merge pull request #242 from mattconnolly/master

Allow libsodium to be installed in a custom path and fix for SmartOS/Solaris build