Description of problem:
Should support empty input of destinationDir on BC editor page.
See https://docs.openshift.org/latest/dev_guide/builds.html#using-secrets-s2i-strategy which says "If you left destinationDir empty, then the secrets are placed in the working directory of the builder image". This means it should be supported.


Version-Release number of selected component (if applicable):
openshift v3.4.0.16

How reproducible:
Always

Steps to Reproduce:
1. Create a BC, prepare secrets
$ oc new-build centos/ruby-22-centos7~https://github.com/openshift/ruby-ex.git
$ oc secrets new-basicauth gitsecret --username=user --password=12345678
$ touch file; oc secrets new mysecret file

2. Login to web openshift console, go to BC ruby-ex editor page: https://<master>:8443/console/project/xxia-test/edit/builds/ruby-ex
Click "advanced options",
1> under the "Build Secret" part, click the box, select a secret, input "/tmp" in "Destination Directory".
2> check the "Add another secret" and "Save" button

3. As comparison, click "Add another secret", in the new input,
1> select a secret, but leave "Destination Directory" empty
2> check the "Add another secret" and "Save" button again

Actual results:
2.
2> After input in "Destination Directory", it enables the "Add another secret" and "Save" button (blue color)

3.
2> When leave "Destination Directory" empty, the "Add another secret" is not shown, "Save" button is gray

Expected results:
3.
2> Should support empty input of destinationDir. When leave "Destination Directory" empty, the "Add another secret" should be shown, "Save" button should be enabled.

Additional info: