### Describe the issue

I added a second new wallet2.dat. Now I wanted to encrypt it, but `bitcoin-cli help` does not show the command to do so, I need to use `bitcoin-cli -rpcwallet=wallet2.dat help`. This is very un-intuitive, and bad for a help function.

### Can you reliably reproduce the issue?

1. have an encrypted default wallet
2. add new multi wallet wallet2.dat via config file or cmd line options
3. naive `bitcoin-cli help` does not show command to encrypt second wallet.

### Expected behaviour

All wallet encryption, lock and unlock commands should be shown unconditionally in `bitcoin-cli help`.

The dynamic hiding of some lines is arguably worse than the benefit with multiple wallets.

### Actual behaviour

`bitcoin-cli help` shows only wallet encryption commands appropriate for the default wallet.

### What version of bitcoin-core are you using?

bitcoind 0.15.0.1~dfsg-1
deb http://ppa.launchpad.net/luke-jr/bitcoin-core-bip148-unofficial-builds/ubuntu zesty main

### Machine specs:
- OS: Debian 9.2

{
    CWallet * const pwallet = GetWalletForJSONRPCRequest(request);
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
    if (request.fHelp || request.params.size() != 1)
        throw std::runtime_error(
            "getaccount \"address\"\n"
            "\nDEPRECATED. Returns the account associated with the given address.\n"
            "\nArguments:\n"
            "1. \"address\"         (string, required) The bitcoin address for account lookup.\n"
            "\nResult:\n"
            "\"accountname\"        (string) the account address\n"
            "\nExamples:\n"
            + HelpExampleCli("getaccount", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\"")
            + HelpExampleRpc("getaccount", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\"")
        );
    LOCK2(cs_main, pwallet->cs_wallet);
    CTxDestination dest = DecodeDestination(request.params[0].get_str());
    if (!IsValidDestination(dest)) {
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid Bitcoin address");
    }
    std::string strAccount;
    std::map<CTxDestination, CAddressBookData>::iterator mi = pwallet->mapAddressBook.find(dest);
    if (mi != pwallet->mapAddressBook.end() && !(*mi).second.name.empty()) {
        strAccount = (*mi).second.name;
    }
    return strAccount;
}
UniValue getaddressesbyaccount(const JSONRPCRequest& request)