start prepublishing generation
add default gitconfig user info to CI
fix invalid error code returns from tests
fix and add tests
Only test master and pull requests on appveyor
Merge pull request #310 from nodegit/fix-publishing

Appveyor seems to be randomly passing and failing this, with no real reason, so we've decided to merge this.
Updated generateMissingTests.js to run once called.
Updated CONTRIBUTING.md with correct missing tests command.
Updated "generate" scripts to run when called via npm.