Add Goals entity and functionality

This is a proposed data object for a new Goals entity and related entities within the TPDM. Currently goals, action steps, and next steps are unsupported and this new entity proposal would provide an object for these and any type of similar target.

In practice, "goals" may be attributed to staff, cohorts/groups, buildings, staff evaluations, or other goals as sub-goals. This object should be extensible enough to handle all of these various implementations (e.g., "next steps" after an evaluation or performance rating, in addition to traditional year- or semester-long staff goals). They also are evaluable against a rubric and can have various types of comments or questions/answers associated to them.

Attached is an initial object model proposal for these new entities, with descriptions and recommended field types. Each sheet in the attached spreadsheet represents an entity. This model is based on our (TeachBoost's) implementation of this type of data over the past 7 years.

• Goals: main entity for goal metadata
• GoalAssignments: relationship table for goal associations to staff, performance measures, etc.
• SurveyGoalAssociations: sometimes goals in practice have questions and answers associated to them; we need a new relationship table to link goals to surveys, the data type that makes the most sense for these questions/answers.

This also contains a few descriptor references, like Goal Type for the various types of goals this can cover.