This puts it more in line with other upcoming options that use "dir"
instead of "directory" (plus it's easier to type), and makes it clear
that this directory and the passthrough behavior is related to the UI as
opposed to other upcoming items.
* Update ui build to use 'admin' folder instead of 'core'
Post release of v0.1.2, ui/core folder has been renamed to ui/admin.
Update ui build scripts to be aware of the path change.
* Update packagespec to reflect "admin" ui folder change