Made createReleaseFolder async with promises
Added getResourcesDirectoryPath function for DRYness
Added safety check that copyFile copies file
Retries if file doesn't exist after copy + ignores chmod errors
Merge branch 'master' of https://github.com/mllrsohn/node-webkit-builder into fixing-1.0.x
Merge pull request #144 from mllrsohn/fixing-1.0.x

Some fixes related to #142