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

@@ -21,7 +21,7 @@ const invites = {
     async FetchInviteTokens({ commit, getters }) {
       commit('SET_LOADING', true)
       const response = await listInviteTokens(getters.authHost, getters.token)
-      commit('SET_TOKENS', response.data.invites)
+      commit('SET_TOKENS', response.data.invites.reverse())
       commit('SET_LOADING', false)
     },
     async GenerateInviteToken({ commit, dispatch, getters }, { maxUse, expiresAt }) {