Fix mem leak in rz_getPropertyNames.
Added a cache for rz_dataTypeForPropertyNamed.
Merge pull request #32 from joe-goullaud/feature/cacheDataTypeForPropertyNamed

Added a cache for rz_dataTypeForPropertyNamed to speed up repeat calls.
Added NULL check before freeing properties in rz_getPropertyNames.
Merge pull request #31 from joe-goullaud/bugfix/memleak

Fix mem leak in rz_getPropertyNames.
No need for null check on free
Fix OCUnit deprecation warning
Merge pull request #33 from Raizlabs/development

Merge bugfixes to master