Set-BuildEnvironment errors if git is not installed.

[juanfperezperez]

Related to #37
When using Set-BuildEnvironment to create the variables in a Linux container that does not have git installed the build script fails because git is not installed. I'm currently getting around it by installing git in a before_script, but that should not be necessary, since I don't use git in these tasks. An option to omit the git check should enable us to not have to install git in order to use this function.

Setting Build Variables
ERROR: The term 'git' is not recognized as the name of a cmdlet, function, script file, or operable program.
Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
At /root/.local/share/powershell/Modules/BuildHelpers/1.0.1/Public/Get-BuildVariables.ps1:78 char:21
+         $GitPath = (Get-Command $GitPath)[0].Path
+                     ~~~~~~~~~~~~~~~~~~~~
Build FAILED. 0 tasks, 1 errors, 0 warnings 00:00:12.6075315
Get-Command : The term 'git' is not recognized as the name of a cmdlet, function, script file, or operable program.
Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
At /root/.local/share/powershell/Modules/BuildHelpers/1.0.1/Public/Get-BuildVariables.ps1:78 char:21
+         $GitPath = (Get-Command $GitPath)[0].Path
+                     ~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo          : ObjectNotFound: (git:String) [Get-Command], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException,Microsoft.PowerShell.Commands.GetCommandCommand

[RamblingCookieMonster]

Good catch! Yeah, that was a bug I think - just pushed with that set that to silentlycontinue, that should get things running (unless we have some logic gate that tries to call git without the $WeCanGit or some other control in place)

Cheers!

[RamblingCookieMonster]

Closing this out - ping me if it's still an issue!