Creates a base model for SLIMS table rows with methods
Creates a model for Instrument table
Adds method that fetches a raw record from SLIMS Instrument table using input_id
Both rig and instrument are in same table, so this method will fetch raw record for both instrument_id and rig_id (We will add separate methods for mapping, and separate endpoints for the 2, but they'll both use this base method of get_instrument_record to get raw record)
closes #174 and #175