Pfio

Fix text mode readlines 189

Bugfix: Fix read(-1) call from S3 StreamBody 183

Release notes:
- `pfio.v2.S3` has become now foolproof. When a process fork is detected and raises an error. (175 )
- `chainerio` namespace has been removed. (179 )
- Now `pfio.v2.S3` supports mutlipart upload. (178 )
- Now fileobject from `pfio.v2.S3` supports `.seek()` method. (170 )

Release note:
- 169 : Do not allow NFS for `FileCache` directory

Release notes:
- 165 Fix last_modified attr in S3ObjectStat
- 166 Fix binary read and write of S3 objects

Thanks to HiroakiMikami for helping a lot.

Release notes:
- 162 Fix broken readers .closed property (S3)