Display progress

[uu59]

Fix #16
Display as below:

$ embulk run foo.yml
2015-06-03 16:11:26.513 +0900: Embulk v0.6.9
2015-06-03 16:11:30.896 +0900 [INFO] (transaction): {done:  0 / 1, running: 0}
2015-06-03 16:11:30.953 +0900 [INFO] (task-0000): Writing local file './sample.000.00.csv'
2015-06-03 16:11:32.840 +0900 [DEBUG] Fetching 1 / 1 page
2015-06-03 16:11:44.502 +0900 [INFO] (transaction): {done:  1 / 1, running: 0}
2015-06-03 16:11:44.527 +0900 [INFO] (main): Committed.
2015-06-03 16:11:44.527 +0900 [INFO] (main): Next config diff: {"in":{},"out":{}}

[yoshihara]

LGTM