ignore node_modules and changed docs to install less globally

.gitignore

@@ -10,10 +10,11 @@ build.py
 **-all.js
 **-min.js
 media/uploads
+node_modules
 tmp
 locale
 docs/_build
 highstock.src.js
 /static
 *.less.css
-.DS_Store
+.DS_Store

docs/hacking_howto.rst

@@ -115,7 +115,7 @@ To install LESS you will first need to `install Node.js and NPM
 
 Now install LESS using::
 
-    $ npm install less
+    $ npm install -g less
 
 
 Getting the Source