Refactor of favorites caching to address MOBSDK-694 and MOBSDK-702.
Fix for MOBSDK-703.
Merge branch 'topic-favorites-cache' (with resolved conflicts)
Merge pull request #273 from gavincornwell/master

MOBSDK-694, MOBSDK-702 and MOBSDK-703
Added back sorting of favourite nodes, cache building delegate is now passed as method parameter rather than property via initialiser to fix memory leak and fixed MOBSDK-709 (also removed debug statements that could reveal API key and secret)
Merge pull request #274 from gavincornwell/master

Caching fixes and MOBSDK-709
MOBSDK-710: Application crashes when user click done button in task