register, login, some search function

changes:
* register.
* login;
* search jids by cellphone number;
* search jid, nickname, photo by cellphone number or email.
*write cellphone number or email into vcard, vcard_search when register.
`Acc0` -> `<<>>`
`<< Result/binary, "]}">>` -> `<<"{\"people\":[", Result/binary, "]}">>`