Figure out why e2e script doesn't catch some issues

[gaearon]

npm run build currently fails due to #162 (comment).
However e2e script didn't catch it.

[dhruska]

I think the issue here is that the e2e script is running the build task with the --debug-template flag, so the relative path in build.js is ./template. When running the actual build task in a new project, that flag isn't set so a different relative path is used. Not sure what the best solution is to prevent this, but that explains the missed error.

[gaearon]

I think it only uses this flag the first time, but it should later create a separate directory and run a regular build there.