Remove gogit and major refactoring (#2)

* Fix typo in readme

* Reimplement all git methods without go-git

* Rename repo pkg to git, add gitconfig methods

* Improve tests for configuration reading

* Rename package file to io and move RepoFinder there

* Refactor printers

- Remove smart printer
- Decouple printers from git repos with interfaces
- Update printer functions
- Remove unnecessary flags
- Add better remote URL detection

* Update readme and go.mod

* Add author to git commit in tests

Otherwise tests will fail in CI.

* Install git before running tests and don't use cgo

* Add better error message, revert installing git

* Ensure commit message is in quotes

* Set up git config before running tests

pkg/git/config.go

@@ -0,0 +1,20 @@
+package git
+
+import "os/exec"
+
+// ConfigGlobal represents a global gitconfig file.
+type ConfigGlobal struct{}
+
+// Get reads a value from global gitconfig file. Returns empty string when key is missing.
+func (c *ConfigGlobal) Get(key string) string {
+	cmd := exec.Command("git", "config", "--global", key)
+	out, err := cmd.Output()
+
+	// In case of error return an empty string, the missing value will fall back to a default.
+	if err != nil {
+		return ""
+	}
+
+	lines := lines(out)
+	return lines[0]
+}