Duplicate name testing is not asserted on prepare shotgun libraries

[wasade]

The library plate name is automatically pulled from the plate name. If this name already exists, the box surrounding the name is red and includes a red X. However, it is still possible to click prepare libraries, and when doing so (with a name that already exists), a traceback results.

[wasade]

A slight twist on this: if a user enters the same name for multiple plates, it is allowed but triggers a traceback.

[wasade]

Note that this behavior seems present on other pages (e.g. normalization)