Update opam file
Remove camlp4
Move git_unix and git_mirage in their own subdirs
Remove warnings
Use dolog 1.0
Update CHANGES
Use a LRU cache instead of an unbunded hashtbl

The LRU code comes from Simon Cruanes's CCache implementation.
Update CHANGES
Remove crazy caching in Git.FS.

Now there is only on LRU in Git.Value associating hashes to inflated contents
Fix compilation on 4.01
Add a test for checking leaks
Look first in the cache for [mem]
modified to eliminate unnecessary buffer allocation
Update CHANGES
Extend the tree values

Import bits of https://github.com/codinuum/ocaml-git/commit/3369291fdce1b21d5ed1e3d32f3c80e2738437a9
Update CHANGES
Update the Travis scripts
Add a broken test for #35
Use atomic rename in Git_unix.IO.write_file

This ensure the operation is atomic and should fix #35
Update CHANGES