Merge pull request #4 from johnpmayer/master

New download link for 64 bit cargo on windows
Updated 32-bit Cargo download link
Switched the one-liner to using BitsTransfer

Bits-Transfer seems to be more robust, the webclient download was failing depending upon the directory you ran the command in. This is also easier to read.
Detect and use installed 7-Zip if available.

Added function Acquire-7z which checks for the presence of a 7-Zip
installation via the registry, and falls back to downloading &
extracting 7za if one isn't found.
Minor beautification of braces and whitespace.

^
Use Join-Path when checking for a 7-Zip install.
Merge pull request #5 from whipsch/master

Detect and use installed 7-Zip if available.