adds calls to calabash-ios-server/calabash/gitversioning scripts
before and after the xcodebuild call.  this is part of the server
versioning strategy.

provides the following additional information when server_version
is executed:

    "git branch" => "0.9.x-add-git-versioning-information",
    "git revision" => "cdce959",
Merge pull request #216 from jmoody/0.9.x-add-git-versioning-information

0.9.x add git versioning information