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/views/table/dynamicTable/fixedThead.vue

-<template>
-  <div class="app-container">
-
-    <div class="filter-container">
-      <el-checkbox-group v-model="checkboxVal">
-        <el-checkbox label="apple">apple</el-checkbox>
-        <el-checkbox label="banana">banana</el-checkbox>
-        <el-checkbox label="orange">orange</el-checkbox>
-      </el-checkbox-group>
-    </div>
-
-    <el-table :data="tableData" :key="key" border fit highlight-current-row style="width: 100%">
-      <el-table-column prop="name" label="fruitName" width="180"/>
-      <el-table-column v-for="fruit in formThead" :key="fruit" :label="fruit">
-        <template slot-scope="scope">
-          {{ scope.row[fruit] }}
-        </template>
-      </el-table-column>
-    </el-table>
-
-  </div>
-</template>
-
-<script>
-const defaultFormThead = ['apple', 'banana']
-
-export default {
-  data: function() {
-    return {
-      tableData: [
-        {
-          name: 'fruit-1',
-          apple: 'apple-10',
-          banana: 'banana-10',
-          orange: 'orange-10'
-        },
-        {
-          name: 'fruit-2',
-          apple: 'apple-20',
-          banana: 'banana-20',
-          orange: 'orange-20'
-        }
-      ],
-      key: 1, // table key
-      formTheadOptions: ['apple', 'banana', 'orange'],
-      checkboxVal: defaultFormThead, // checkboxVal
-      formThead: defaultFormThead // 默认表头 Default header
-    }
-  },
-  watch: {
-    checkboxVal(valArr) {
-      this.formThead = this.formTheadOptions.filter(i => valArr.indexOf(i) >= 0)
-      this.key = this.key + 1// 为了保证table 每次都会重渲 In order to ensure the table will be re-rendered each time
-    }
-  }
-}
-</script>
-