Improve `_cs` output

[Manfred Touron]

Try to get something similar to s3cmd output

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• list containers -> you won't have all the needed informations using only this API, so just print the name

$ s3cmd ls
2014-10-18 16:38  s3://moul
2014-10-18 16:38  s3://manfredtouron
...

---

• list container contents: here you can get an equivalent output

$ s3cmd ls s3://moul
                       DIR   s3://moul/3.19.8-std/
                       DIR   s3://moul/4.0.2-std/
                       DIR   s3://moul/4.1-std/
                       DIR   s3://moul/tmp/
2015-01-16 11:46 100000000   s3://moul/100Mo.dat
2015-03-11 11:56 100000000   s3://moul/101Mo.dat
2015-05-08 15:39     15930   s3://moul/bitrig-bsd-dtb
2015-05-12 13:08  26460224   s3://moul/bitrig-bsd-uImage
2015-09-04 13:33     16674   s3://moul/dev-dtb
2015-09-04 14:42   3339272   s3://moul/dev-uImage
...