Revert "use sv_yes and sv_no instead of creating a new SV"

This reverts commit be6b2de57d68341cd9e32676b8f7925967fe6971.
Repository.xs: make status() return all files' statuses (closes #29)
xs: newline after PROTOTYPE
Repository.xs: actually use git_status_option
Commit.xs: add summary() method
Commit.pm: document summary()
Repository.xs: implement is_shallow(), state() and state_cleanup() methods
Repository.pm: document for is_shallow(), state() and state_cleanup()
Repository.xs: implement new clone options

* remote_name
* checkout_branch
* ignore_cert_errors
* disable_checkout_options
Repository.pm: document new clone options

* remote_name
* checkout_branch
* ignore_cert_errors
* disable_checkout
Changes: update