More model tests written. Additionally added some missing relations to the models.

modified:   app/models/analysis_item.rb
modified:   app/models/analysis_job.rb
modified:   app/models/analysis_script.rb
modified:   app/models/audio_recording.rb
modified:   app/models/saved_search.rb
modified:   app/models/user.rb
new file:   spec/factories/analysis_item_factory.rb
new file:   spec/factories/analysis_job_factory.rb
new file:   spec/factories/analysis_script_factory.rb
modified:   spec/models/analysis_item_spec.rb
modified:   spec/models/analysis_job_spec.rb
modified:   spec/models/audio_event_spec.rb
modified:   spec/models/audio_recording_spec.rb