Support Clinical pay scales

Created by: rjw57

Support the nodal points, consultant, research associate and lecturer pay scales for the clinical school. These are represented via a separate salary scale table since their negotiated increment sates are different.

The main commits are 2c22ff7e and cb0c8727 which adds the data itself and wires the table in as a new constant.

Since salary progression information is currently a little obscure, we model all points as "contribution" points meaning that progression is not automatic.

Closes #11 (closed)