add unit test for serving static paths.
Fix 'meteor test-packages --production onepackage'.

We were looking at "argv._" to find package names, where that was the argv that
was parsed at the top level, where we had no idea that "--production" was a
boolean, so it was pased as "--production=onepackage" and "onepackage" was not
included in argv._.
Make new test pass with --production.
Merge branch 'devel' into linker