Adapt to new download URL for Git for Windows

The download URLs for Git for Windows are now
hosted on GitHub
updates prior to automatic run for 20140602_083548
Set path system wide when installing git.commandline/git.install.
updates prior to automatic run for 20140603_054327
Merge pull request #80 from TomOne/git-download-fix

Adapt to new download URL for Git for Windows
Update chocolateyInstall.ps1
update backup
updates prior to automatic run for 20140604_054002
Merge pull request #81 from gildor478/machine-wide-git.install

Set path system wide when installing git.install.
updates prior to automatic run for 20140606_054000
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