Add approved boolean to Organizations

[joshsmith]

Problem

We need to add an approved boolean value to organizations that can only be set by a Code Corps admin.

Subtasks

• Create the migration
• Write the model tests
• Create an approval changeset
• Write the controller tests
• Add filtering with the boolean to the index
• Write the view tests
• Add to the view

[dleve123]

Going to try to tackle this!