Implemented more robust unicode handling.

* Immediatelly convert all args from `bytes` to `str`.
* Added `Environment.stdin_encoding` and `Environment.stdout_encoding`
* Allow unicode characters in HTTP headers and basic auth credentials
  by encoding them using UTF8 instead of latin1 (#212).

httpie/plugins/builtin.py

@@ -1,3 +1,5 @@
+from base64 import b64encode
+
 import requests.auth
 
 from .base import AuthPlugin
@@ -8,13 +10,28 @@ class BuiltinAuthPlugin(AuthPlugin):
     package_name = '(builtin)'
 
 
+class HTTPBasicAuth(requests.auth.HTTPBasicAuth):
+
+    def __call__(self, r):
+        """
+        Override username/password serialization to allow unicode.
+
+        See https://github.com/jkbr/httpie/issues/212
+
+        """
+        credentials = u'%s:%s' % (self.username, self.password)
+        token = b64encode(credentials.encode('utf8')).strip()
+        r.headers['Authorization'] = 'Basic %s' % token
+        return r
+
+
 class BasicAuthPlugin(BuiltinAuthPlugin):
 
     name = 'Basic HTTP auth'
     auth_type = 'basic'
 
     def get_auth(self, username, password):
-        return requests.auth.HTTPBasicAuth(username, password)
+        return HTTPBasicAuth(username, password)
 
 
 class DigestAuthPlugin(BuiltinAuthPlugin):