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 #59 from JorgeRaimundo/master

Multiple user ids for memberships
Merge pull request #60 from JanMalte/patch-1

Improve fetching items with high limits
cs fixes
fix attachCustomFieldXML + add TestClient class returning raw xml on post/put calls + add issue xml tests
add project xml tests
add user + issue cat xml tests
add membership + wiki cat xml tests
add path & method test (wiki)
add path & method test for all apis
added skip of new iteration if no limit can set

If the response don't has the "limit" key, no limit can be set and therefor we don't need a further iteration. Maybe the complete part should be refactored some day.
change array_key_exists to isset to keep code consistant
fixed failing test due to date() call
Merge pull request #62 from JanMalte/patch-1

added skip of new iteration if no limit can be set
Merge pull request #65 from JanMalte/patch-2

fixed failing test due to date() call
cleaned up getPort method
Merge pull request #66 from JanMalte/getPort

cleaned up getPort method
added unit tests for unsupported methods of test client