Send email invitation to the user to join to the group
| groupid | id of the group |
| emailid | email of the user to which invitation is sent |
| emailreplyto | email of the user from which invitation is sent |
| message | message of the invitation |
<commands>
<command>
<type>inviteusertogroup</type>
<result> { 0 | 1 } </result>
<message> { OPTIONAL ERROR STRING or REASON } </message>
</command>
</commands>
Requirements: