[1.3.x] Users account.php updated to avoid E_WARNING

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | -
| Fixed tickets | -
| Refs tickets  | -
| License       | MIT
| Doc PR        | -

Going to the Users panel (http://localhost:8888/zk138/Users) in the current Zikula 1.3.x gives the following E_WARNING on PHP 5.4.10. 

WARN (4): E_WARNING: Invalid argument supplied for foreach() in /Volumes/DATA_ES/MAMP_htdocs/zk138/system/Users/lib/Users/Api/Account.php line 59

I've adapted that line to make sure an extra check is done on the existence of an array variable. That removes the E_WARNING. Also the method call to Blocks api getAll was with a capital, where the method in Blocks is not.