Reform OperationalStatus codes

OperationalStatus seems to be principally an EDFacts enumeration, but it does not map to that list. See https://www2.ed.gov/about/inits/ed/edfacts/eden/non-xml/n029-11-2.doc

Two issues:

1. There is an OperationalStatus (currently a type under 2.0, but to be a descriptor under 3.0) value of "Continuing" and no one seems to know what this value means or where it came from. It also does not map to any CEDS value. The proposed action is to remove the value if we can't determine its meaning or what use case it is associated with.
2. The value of "Changed Agency" does not clearly map to the EDFacts value of "Changed", because the name suggests the semantics of the School definition "School is operational but was previously reported as affiliated with a different LEA." The LEA Changed value is concerned with Boundary changes. As a result, the semantics are confused. The solution seems to be to remove "Changed Agency" and replace it with "Changed" or introduce a new value called "Changed Boundary"