Generate invite tokens from admin-fe

This MR allows to create invite tokens, list them on a separate tab, invite users via email. It also updates error handling and allows to generate tokens for resetting password.

Closes #28 (closed)

src/store/modules/invites.js

@@ -14,7 +14,7 @@ const invites = {
       state.newToken = token
     },
     SET_TOKENS: (state, tokens) => {
-      state.inviteTokens = tokens.reverse()
+      state.inviteTokens = tokens
     }
   },
   actions: {