academic_term not copied to Program Enrollment

[johnwslongland]

When creating Program Enrollment from Student Applicant, the
'academic_term' is not copied from the Student Applicant to
Program Enrollment

Replication:

1. Log on to server
2. Assumes Program, Course, Topic already exists
3. Create new Student Applicant
4. Complete all fields including 'academic_term'
5. "Approve" the Student Applicant'
6. Clilck "Enroll" to enroll the student
7. User is taken to newly created Program Enrollment in DRAFT state

Observation:
The 'academic_term' field is not populated

Expected behaviour:
The 'academic_term' field on Program Enrollment should contain the
value on Student Application

Fix:
Two changes required in API.PY

Will submit PR