text: Title: Legend colors are not updated when colors are set with format strings or color kwarg
  Body: The legend colors are set by the palette and not updated when the colors are specified manually.  To replicate the bug:
  
  ```
  # import
  import hypertools as hyp
  import numpy as np
  from scipy.stats import multivariate_normal
  
  # simulate clusters
  cluster1 = np.random.multivariate_normal(np.zeros(3), np.eye(3), size=100)
  cluster2 = np.random.multivariate_normal(np.zeros(3)+3, np.eye(3), size=100)
  
  # plot
  hyp.plot([cluster1, cluster2], ['k', 'r'], legend=['cluster1', 'cluster2'])
  ```
  
  outputs this:
  
  ![download](https://user-images.githubusercontent.com/6596567/32500822-71e80086-c3a4-11e7-9ebb-2512fd9120a2.png)
  
  