hardware_products + json_schemas

[karenetheridge]

Add database and api endpoint support for associating json_schemas with hardware_products

new endpoints:

• POST /hardware_product/:hardware_product_id_or_other/json_schema/:json_schema_id
• POST /hardware_product/:hardware_product_id_or_other/json_schema/:json_schema_type/:json_schema_name/:json_schema_version
• GET /hardware_product/:hardware_product_id_or_other/json_schema
• DELETE /hardware_product/:hardware_product_id_or_other/json_schema/:json_schema_id
• DELETE /hardware_product/:hardware_product_id_or_other/json_schema/:json_schema_type/:json_schema_name/:json_schema_version
• DELETE /hardware_product/:hardware_product_id_or_other/json_schema

Also add ?with_hardware_products=1 option to GET /json_schema/:type/... endpoints for listing the hardware_products that make use of that JSON Schema.