title: how to clone git repository with submodules without asking for password for every subrepository
body: <p>I'm recently put a repository into bitbucket. And this repository has some submodules</p>
  
  <p>I'm working on a Initialization script. I would like to clone the main directory and them pull all subdirectories.</p>
  
  <pre><code> git clone https://bitbucket.org/#####/main.git elastic --recurse-submodules
  </code></pre>
  
  <p>this prompts me for the user and password. </p>
  
  <pre><code>Username for 'https://bitbucket.org': myuser 
  Password for 'https://myuser@bitbucket.org': 
  </code></pre>
  
  <p>and them it asks me again for every submodule</p>
  
  <pre><code>Username for 'https://bitbucket.org':  
  ...
  </code></pre>
  
  <p>My .gitmodules file is like:</p>
  
  <pre><code>[submodule "api"]
       path = app/api/
       url = git@bitbucket.org/###/api.git
       branch = master
  [submodule "front"]
       path = app/front
       url = git@bitbucket.org/###/front.git
       branch = master
  [submodule "app/config"]
       path = app/config
       url = git@bitbucket.org/###/config.git
       branch = master
  
  ... some few more repositories
  </code></pre>
  
  <p>How can I clone the main repository and them use the same credentials to all childs repositories?</p>
  
  <p>I'm using AWS AMI Linux.</p>