Admin extra interface

[ludwikbukowski]

I tried to make admin interface more hospitable. It should do some checks on input and inform about result of command.
Improved following modules:

• mod_admin_extra_accounts
• mod_admin_extra_last
• mod_admin_extra_private
• mod_admin_extra_roster
• mod_admin_extra_stanza
• mod_admin_extra_stats
• mod_admin_extra_vcard

[michalwski]

@ludwikbukowski sth's wrong with ejabberdctl_SUITE:vcard_rw because all jobs failed except the one using external authentication (where this test case is probably not run).

[michalwski]

I think this check should be moved to the main function which is set_password unless do_set_password is used directly from other places.

[ludwikbukowski]

Remember to add specs for exported functions and also change specs when you modify functions

[michalwski]

I see that most (if not all) commands you touched have now result type {res, restuple}. This is correct, but not much informative. How about spending some more time and defining more precise result types. A good example maybe command connected_users_info. Which you can find in mod_admin_extra_sessions module. The result type for this command looks like the following (in shell).

mongooseimctl help connected_users_info

  Command Name: connected_users_info

  Arguments:

  Returns: connected_users_info::[ sessions::{ jid::string,
                                               connection::string,
                                               ip::string,
                                               port::integer,
                                               priority::integer,
                                               node::string,
                                               uptime::integer } ]

  Tags: session

  Description: List all established sessions and their information

Also I think we can remove the unnecessary empty lines in the help output above.

[erszcz]

I noticed this on Travis when testing stuff rebased on top of this PR:

ejabberdctl_SUITE.erl:750: Warning: use of operator '=/=' has no effect
ejabberdctl_SUITE.erl:751: Warning: use of operator '=/=' has no effect

Which makes sense, since these lines are not assertions! They evaluate to a boolean() which is then discarded.

Please rewrite to:

true = Err1 =/= 0

or

?assertNotEqual(0, Err1)

or

?assert(Err1 =/= 0)