Mode improvements for UI (#3109)

* `--mode=off` now works.

* Add Mode::Off as a persistent CLI option.

* "last" not "auto" as default.

* Commit accidentally unsaved file.

* Whitespace

[ci:skip]

* Mode CLI parse fix

* or offline

* Save mode when it gets changed.

* Fix Offline mode

* Fix up mode operations.

* Make passive default, but not overriding.

* Fix test

* Maybe not everyone wants to run an archive node...

mac/post-install.sh

@@ -11,8 +11,6 @@ cat > $HOME/Library/LaunchAgents/io.parity.ethereum.plist <<EOF
     <key>ProgramArguments</key>
     <array>
         <string>/usr/local/libexec/parity</string>
-        <string>--mode</string>
-        <string>passive</string>
         <string>--warp</string>
     </array>
     <key>KeepAlive</key>
@@ -26,9 +24,11 @@ cat > $HOME/Library/LaunchAgents/io.parity.ethereum.plist <<EOF
 </dict>
 </plist>
 EOF
-mkdir -p $HOME/.parity
 
-chown $USER $HOME/.parity $HOME/Library/LaunchAgents $HOME/Library/LaunchAgents/io.parity.ethereum.plist
+mkdir -p $HOME/.parity/906a34e69aec8c0d
+echo -n '{"fat_db":false,"mode":"passive","pruning":"fast","tracing":false}' > $HOME/.parity/906a34e69aec8c0d/user_defaults
+
+chown -R $USER $HOME/.parity $HOME/Library/LaunchAgents $HOME/Library/LaunchAgents/io.parity.ethereum.plist
 
 su $USER -c "launchctl load $HOME/Library/LaunchAgents/io.parity.ethereum.plist"
 sleep 1