Support loading eslint from node_modules, re issue #118.

test/test_resolve_local_path.vader

@@ -0,0 +1,15 @@
+Execute(Open a file some directory down):
+  silent! cd /testplugin/test
+  :e! top/middle/bottom/dummy.txt
+
+Then(We should be able to to find the local version of a file):
+  AssertEqual
+  \ expand('%:p:h:h:h:h') . '/top/example.ini',
+  \  ale#util#ResolveLocalPath(bufnr('%'), 'example.ini', '/global/config.ini')
+
+Execute(Do nothing):
+
+Then(We shouldn't find anything for files which don't match):
+  AssertEqual
+  \ '/global/config.ini',
+  \  ale#util#ResolveLocalPath(bufnr('%'), 'missing.ini', '/global/config.ini')