Improve analyzer performance when the number of runs are large

fixed #248

-  improve analysis on_ps performance
  - apply aggregation pipeline to collect run ids
  - make links run.dirs instead of run.result_paths to _input directory
 
### Performance Test
- Settings
  - 160 runs
  - dummy analyzer (command: "echo")
- Analyzing Time
  - old specification: 1065 sec
  - new specification: 7 sec

ここのqueryはaggregation pipelineを使わずに `ps.runs.where(status: :finished).only(:id)` と書けば良い気がします。