Admin manage pending accounts

A few new features for Users view related to pending accounts:

• Adds new "pending" status for filters and labels
• Ability to approve and reject pending accounts (rejecting an account deletes it)
• Ability to view "reason for joining" when filtered by pending accounts (truncated to 100 chars)
• Ability to view full "reason for joining" on user show page

src/api/__mocks__/users.js

 export let users = [
-  { active: true, deactivated: false, id: '2', nickname: 'allis', local: true, external: false, roles: { admin: true, moderator: false }, tags: [] },
-  { active: true, deactivated: false, id: '10', nickname: 'bob', local: false, external: true, roles: { admin: false, moderator: false }, tags: ['mrf_tag:sandbox'] },
-  { active: false, deactivated: true, id: 'abc', nickname: 'john', local: true, external: false, roles: { admin: false, moderator: false }, tags: ['mrf_tag:media-strip'] }
+  { active: true, approval_pending: false, deactivated: false, id: '2', nickname: 'allis', local: true, external: false, roles: { admin: true, moderator: false }, tags: [] },
+  { active: true, approval_pending: false, deactivated: false, id: '10', nickname: 'bob', local: false, external: true, roles: { admin: false, moderator: false }, tags: ['mrf_tag:sandbox'] },
+  { active: false, approval_pending: false, deactivated: true, id: 'abc', nickname: 'john', local: true, external: false, roles: { admin: false, moderator: false }, tags: ['mrf_tag:media-strip'] },
+  { active: true, approval_pending: true, deactivated: false, id: '100', nickname: 'sally', local: true, external: false, roles: { admin: false, moderator: false }, tags: [] }
 ]
 
 const userProfile = { avatar: 'avatar.jpg', nickname: 'allis', id: '2', tags: [], roles: { admin: true, moderator: false }, local: true, external: false }
@@ -85,6 +86,14 @@ export async function deactivateUsers(nicknames, authHost, token) {
   return Promise.resolve({ data: response })
 }
 
+export async function approveUserAccount(nicknames, authHost, token) {
+  const response = nicknames.map(nickname => {
+    const currentUser = users.find(user => user.nickname === nickname)
+    return { ...currentUser, approval_pending: false }
+  })
+  return Promise.resolve({ data: response })
+}
+
 export async function deleteRight(nickname, right, authHost, token) {
   return Promise.resolve({ data:
     { [`is_${right}`]: false }