Support filter-clean filter-smudge, pull, push for large file size in Windows v.s. S3

[zelonght]

With this PR #28 we can use S3 as Backend.

But we run into limitation of 4GB for file in Windows when running filter-clean and filter-smudge, here is a workaround: PersonifyInc@7a1ec14

Then we run into another issue of upload large file to S3 due to S3 limitation of upload single part, here is a solution for it PersonifyInc@c026fcf

Would be great if we can add S3 support and then those 2 commits to make git-fat support S3 better.

[quangnt]

These solutions are only tested in Windows OS.
Note:

• To support filter-clean and filter-smudge work with >= 4GBs file size requires to install Git 64 bit and Windows 64bit.
• To support upload large file size on Windows >=5 GBs, requires to install python library 'filechunkio' by run command pip install filechunkio