fixed not an array error in AbstractApi.php

This will fix array_merge_recursive(): Argument #2 is not an array in redmine-api/lib/Redmine/Api/AbstractApi.php:121
added break condition for high limits

This will add a break condition to while loop for high limits, if the last data set is retrieved from redmine
fixed break condition for failed requests
Merge pull request #60 from JanMalte/patch-1

Improve fetching items with high limits