WIP: Correctly install OSX .pkg format

[hickey]

This is the change that allows OSX to install crc starting with version 1.27.1.

This change will contain conflicts once GH-3 has been accepted and merged. Once GH-3 has been merged, I will rebase against current master and resolve the conflicts. The only real change will be that the echo line that displays the size of the download file needs to be moved into each path of the if statement. In my testing I used the following:

file_size=$(curl -sI $download | grep "Content-Length:" | sed 's/Content-Length: //g' | tr -d '[:space:]')
echo "This is a large file to download: $(format_num ${file_size})"

Closes #2

[hickey]

My testing is still on going (as pulling 3.26GB is not exactly fast), so there might be one or two minor changes to the installer line. Hopefully that will be resolved before any action is to be taken on this PR.

[hickey]

I am going to rebase and bring in the changes from master, but there are a few issues with the installer. So it is going to be a bit more time to work out how to make installer properly install the binaries in $install_path.