title: Zero initialiser for biases using get_variable in tensorflow
body: <p>A code I'm modifying is using <code>tf.get_variable</code> for weight variables, and <code>tf.Variable</code> for bias initialisation. After some searching, it seems that <code>get_variable</code> should always be favoured due to its portability in regards to sharing. So I tried to change the bias variable to <code>get_variable</code> but can't seem to get it to work.</p>
  
  <p>Original: <code>tf.Variable(tf.zeros([128]), trainable=True, name="b1")</code></p>
  
  <p>My attempt: <code>tf.get_variable(name="b1", shape=[128], initializer=tf.zeros_initializer(shape=[128]))</code></p>
  
  <p>I get an error saying that the shape should not be specified for constants. But removing the shape then throws an error for no arguments.</p>
  
  <p>I'm very new to <code>tf</code> so I'm probably misunderstanding something fundamental here. Thanks for the help in advance :) </p>