Merge pull request #433 from AndyScherzinger/master

Prepare release 2.5.2
Merge pull request #435 from AndyScherzinger/master

Implementation for #434
use ACRA 4.5.0
Merge pull request #439 from nelenkov/dev

use ACRA 4.5.0
removed v1 code
Merge pull request #440 from nelenkov/dev

removed v1 code
state changed key
Merge pull request #442 from nelenkov/dev

state changed key
API Updated. Closes #441