Refactor user settings

Use resources instead of custom controllers, following the Rails way
and making things much cleaner in the process.

app/views/shared/_main_nav.html.erb

@@ -6,5 +6,5 @@
       class: main_nav_class(@current_section, :invitations) %>
 <%= link_to "Wallet", wallet_path,
       class: main_nav_class(@current_section, :wallet) %>
-<%= link_to "Settings", settings_profile_path,
+<%= link_to "Settings", settings_path,
       class: main_nav_class(@current_section, :settings) %>

app/views/shared/_sidenav_settings.html.erb

@@ -1,10 +1,10 @@
 <%= render SidenavLinkComponent.new(
-  name: "Profile", path: settings_profile_path, icon: "user",
-  active: current_page?(settings_profile_path)
+  name: "Profile", path: setting_path(:profile), icon: "user",
+  active: current_page?(setting_path(:profile))
 ) %>
 <%= render SidenavLinkComponent.new(
-  name: "Account", path: settings_account_path, icon: "key",
-  active: current_page?(settings_account_path)
+  name: "Account", path: setting_path(:account), icon: "key",
+  active: current_page?(setting_path(:account))
 ) %>
 <%= render SidenavLinkComponent.new(
   name: "Security", path: "#", icon: "shield", disabled: true