title: send_static_file not picking up from static folder at root in Blueprint
body: <p>From the <code>views.py</code> inside my blueprint, im trying to use the <code>send_static_file</code> to deliver an <code>index.html</code> and just cant get it to work</p>
  
  <p>I have a blueprint called main which I initialize as such in the <code>__init__.py</code> under the blueprint folder <code>mod_main</code></p>
  
  <pre><code>from flask import Blueprint 
  mod_main = Blueprint('main',name,static_folder='/static', static_url_path='/static') 
  from . import views
  </code></pre>
  
  <p>In my main <code>app</code> initialization in the <code>__init__.py</code> under the root <code>app</code> folder</p>
  
  <pre><code>app = Flask(__name__)
  from .mod_main import mod_main as main_blueprint
  app.register_blueprint(main_blueprint,url_prefix='/main')
  </code></pre>
  
  <p>Under the <code>views.py</code> file in the blueprint main (<code>mod_main</code> folder)</p>
  
  <pre><code>@mod_main.route('/')
  def index():
      return mod_main.send_static_file('index.html')
  </code></pre>
  
  <p>But it keeps resolving to <code>404 Not found</code>. Any clue how i can serve the <code>index.html</code> that is under the <code>static</code> folder in the root <code>app</code> folder (I can get it to work if i create a static folder inside the blueprint. But i would like to deliver it from the root <code>app</code>)</p>
  
  <p>Heres the structure with the essential files</p>
  
  <pre><code>app
  |
  -- mod_main/
     |
      -- views.py
      -- __init__.py
  
  -- __init__.py
  
  -- static /
     |
      -- index.html
  </code></pre>