[Forms] Fix select control

[VWoeltjen]

Use ng-show instead of ng-if to suppress the
'Select One' option after user has chosen something
in a select box; the latter appears to be incompatible
with Angular 1.4.x. #113

[VWoeltjen]

Author Checklist

1. Changes address original issue? Y
2. Unit tests included and/or updated with changes? N/A (changes to template only)
3. Command line build passes? Y
4. Expect to pass code review? Y

[larkin]

Review Checklist

1. Changes appear to address issue? Y
2. Appropriate unit tests included? Y
3. Code style and in-line documentation are appropriate? Y
4. Commit messages meet standards? Y
5. Project-specific information isolated to appropriate branches? Y

Integration Checklist

1. Automated build passing after merge? Y
2. No merge conflicts (or resolution trivial/obvious)? Y
3. All master branches up-to-date after merge? Y
4. Project-specific information isolated to appropriate branches? Y