Run vint (vim lint) as part of our Travis checks (#9)

Author: jparise

.travis.yml

@@ -1,6 +1,10 @@
-language: vim
+language: python
 before_install: |
   sudo apt-get -qq update
   sudo apt-get -y install vim
+install:
+  pip install vim-vint==0.3.14
+cache: pip
 script:
+  - make lint
   - make test

Makefile

@@ -1,6 +1,9 @@
 .PHONY: test
 
-all: test
+all: lint test
+
+lint:
+	vint -s after ftdetect ftplugin indent plugin syntax
 
 test: test/vader.vim test/vim-javascript
 	cd test && vim -Nu vimrc -c 'Vader! *' > /dev/null