0.7.2

• The Mock#assert error message now prints out the last unmatched request as well:

  Expected 1 request(s) to:
  
  POST /users
  bob
  
  ...but received 0
  
  The last unmatched request was:
  
  POST /users
  content-length: 5
  alice
  

• Turned request headers into Vec, instead of HashMap to solve the sorting problem once and for all.
• Namespaced the internal API with /mockito.