App creation wizard should allow non-url (i.e. system/admin) buildpacks

[mcelep]

App creation wizard expects to have a valid url in the buildpack field which is wrong behavior. Users should be able to specify a system or admin buildpack in this field.
If a manifest with a non-url buildpack name is present, the buildpack field is populated correctly and validation does not get triggered.

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this. You can view the current status of your issue at: https://www.pivotaltracker.com/story/show/105045114.