Move Travis targets to Makefile

This allows for calling them easily locally.

Makefile

@@ -0,0 +1,16 @@
+test:
+	py.test
+
+build:
+	mkdir $@
+build/vint: | build
+	virtualenv $@
+	$@/bin/pip install vim-vint
+check: LINT_FILES:=after autoload ftplugin plugin
+check: build/vint
+	build/vint/bin/vint $(LINT_FILES)
+
+clean:
+	rm -rf .cache build
+
+.PHONY: test check clean