Override RequestHandler.write to also serialize lists
Add method for writing of error messages

This will allow you to call self.write_error() with an object that has
error_message and error_code attributes.
Merge branch 'master' into serialize_lists

* master:
  fixed Cyclone behaviour: now both dict and list are JSON
  removed 'Welcome Token' concept, obsoleted by #58 and by receiver username specifiation
  solved #58, update API

Conflicts:
	globaleaks/handlers/base.py
Replace json_write with write
Merge pull request #60 from hellais/serialize_lists

Serialize lists