Replaced install_dependencie with Makefile, updated readme

Makefile

@@ -0,0 +1,20 @@
+.PHONY: test all build libgit2
+
+# default task invoked while running make
+all: libgit2 build
+
+export CGO_ENABLED=1
+
+# build and install libgit2
+libgit2:
+	git submodule update --init --recursive
+	cd git2go; make install-static
+
+# go build tags
+TAGS = "static"
+
+build:
+	go build -v -tags=$(TAGS) .
+
+test:
+	go test -v -tags=$(TAGS) ./...