Fix `Log._getCallerDetails()` regex.

1. Now it matches `logging:test`, not `logging:tests`.
2. Now it is okay with server-side source maps, by matching
`/packages/logging/foo.js` in addition to `/packages/logging.js`.
Fix static file serving test.

Test assets are now served under /packages/<package name>:test/.
renaming soure to versions_from in package-source api
Seriously, use the project versions as constraints

(Note: the deleted commented out code would have been erroring had it
been enabled!)
camelcase api.versionsFrom and api.addFiles

Leave around api.add_files so as to not break literally every
package. Leave our own uses of it alone until after merging to devel, so
that merging package.js files isn't a nightmare.
deploy targets linux. bundler takes --architecture
vbump