Update Git plugin version in template

This is a temporary fix until Kannan integrates his new changes into the cookbook. We have a template which fills in git user name and email in Jenkins config. It has a hardcoded version number. If the Git plugin version increases (such as this case from 1.5.0 to 2.0), Jenkins gives a warning. This doesn't really affect anything but is not ideal. In the future, we can access the installed Git version number from a hash, that queries Jenkins directly.