Update binaries to 69db893

https://github.com/libgit2/libgit2/compare/091165c...69db893
Enforce Clone() test coverage

Fix #701
Ensure Tags can be created in detached Head state

Fix #791
Minor fix
Remove trailing whitespaces
Drop tests that rely on the global configuration

We cannot make correct assumptions regarding the fact that the
environment that host the test runner:

 - Contains a global git config file
 - Grants the test runner process with enough rights to write to this file
 - That this file already contains an expected entry

Given those constraints, those tests are removed.
Release LibGit2Sharp v0.19
Use mono 3.6