Update to libgit2 v0.13.0
Fix issue #22, pygit2 compiles again with Python 2.5
Fix compilation warnings, remove unused variables
Fixed reference tests, they were dependent on the order of the file-system, which in fact is undetermined. Sorting them to assure order
Merge pull request #24 from gitpython-developers/test_fixes

Fixed reference tests on linux
allow 20 byte sha strings

Adjusted py_str_to_git_oid to allow 20 byte binary strings. This improves usability to other clients which already store their shas as binary strings, increasing overall performance as they won't have to convert them into hex beforehand, which would have to be converted back to binary form by libgit2 in turn.
Adjusted tests to accept binary shas.
Fixed memory leaks

Repository_read would not free the odb object after using it.
Object_read_raw didn't close the odb object after usage
Making the Tree object iterable.

By copying IndexIter functions, this gives us the ability to iterate of
TreeEntries of a Tree object.
Adding a test on Tree objects iteration.
Merge commit 'byron/repo_write_improved~2'
Merge remote branch 'julien/tree_iter'
Adding a new 'mode' attribute to IndexEntry objects.

This new attribute gives use read access on IndexEntry's mode.
Adding a test on IndexEntry 'mode' new attribute.
Update to libgit2 v0.14.0
Fix memory leak in 'wrap_index_entry' (issue #18)
Repository.write implemented

Implemented Repository write function, using odb write streams
Added simple test
Merge remote branch 'byron/repo_write_improved' into repo_write
Fix coding style

- do not use tabs
- remove trailing white spaces
- lines are 79 chars max.
Reuse the function 'git_oid_to_py_str'
Small improvements of the documentation (commit and iterable trees)