BUG: Check return value on git_config_find_global.

git_config_find_global was not returning 0 due to not having a global
configuration set. This was causing an issue with the following error message

fileops.c:154: git_futils_readbuffer_updated: Assertion `buf && path && *path' failed.
BUG: Pass name of the commiter back and not their email
Change how Test-commit works

Test-Commit has been changed to work with the gtest test
framework. More tests have been added to the suite.

As a bonus, making these changes actually found a bug! The shock
the horror!