add `fab components`

installs components with bower

IPython/frontend/html/notebook/fabfile.py

@@ -9,15 +9,19 b" components_dir = os.path.join(static_dir,'components')"
 
 def test_component(name):
     if not os.path.exists(os.path.join(components_dir,name)):
-        abort('cannot continue without component {}.'.format(name))
+        components()
 
+def components():
+    """install components with bower"""
+    with lcd(static_dir):
+        local('bower install')
 
 def css(minify=True):
     """generate the css from less files"""
     test_component('bootstrap')
     test_component('less.js')
     if minify not in ['True','False',True,False]:
-        abort('need to get Boolean')
+        abort('minify must be Boolean')
     minify = (minify in ['True',True])
 
     min_flag= '-x' if minify is True else ''