Don't run exclude regexp on absolute path

[mstruebing]

Currently the regular expression of the default excludes are run on the whole absolute path but it should rather run on the relative path of the project root somehow.

For example for this repository, git would match (read exclude) all of this and much more (because of the github.com):

git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/Makefile
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/README.md
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/bin/ec
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/cmd/editorconfig-checker/main.go
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/cmd/editorconfig-checker/main_test.go
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/coverage.txt
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/docs/logo.png
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/pkg/types/types.go
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/pkg/utils/utils.go
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/pkg/utils/utils_test.go
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/pkg/validators/validators.go
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/pkg/validators/validators_test.go
git /home/maex/go/src/github.com/editorconfig-checker/editorconfig-checker.go/tags