Added urlview keybinding

1.  A shortcut of 'b' was used as the default binding for passing
comment body text to urlview (this is similar to the default of C-b in
the 'mutt' text email client)
2.  The `comment_urlview` SubmissionController function was added to
recieve the SUBMISSION_OPEN_IN_URLVIEWER keypress request.
3.  The `open_urlview` terminal function was added to handle the urlview
request.  It passes the comment body data to urlview via a Popen
process.
4.  A test case was added to ensure this new code path is executed
5.  Small formatting changes, mostly line length

rtv/terminal.py

@@ -349,7 +349,8 @@ class Terminal(object):
                                 'Browser exited with status=%s' % code)
                         time.sleep(0.01)
                     else:
-                        raise exceptions.BrowserError('Timeout opening browser')
+                        raise exceptions.BrowserError(
+                            'Timeout opening browser')
                 finally:
                     # Can't check the loader exception because the oauth module
                     # supersedes this loader and we need to always kill the
@@ -438,6 +439,20 @@ class Terminal(object):
             else:
                 _logger.info('File deleted: %s', filepath)
 
+    def open_urlview(self, data):
+        urlview = os.getenv('RTV_URLVIEWER') or 'urlview'
+        try:
+            with self.suspend():
+                p = subprocess.Popen([urlview],
+                                     stdin=subprocess.PIPE)
+                try:
+                    p.communicate(input=six.b(data))
+                except KeyboardInterrupt:
+                    p.terminate()
+        except OSError:
+            self.show_notification(
+                'Could not open urls with {}'.format(urlview))
+
     def text_input(self, window, allow_resize=False):
         """
         Transform a window into a text box that will accept user input and loop
@@ -574,4 +589,4 @@ class Terminal(object):
                 break
 
         out = '\n'.join(stack)
-        return out
+        return out