Remove following compilation warnings in develop branch:

```
xively.c:248:7: warning: initialization from incompatible pointer type [enabled by default]
xively.c:248:7: warning: (near initialization for 'FACTORY_ENTRIES[0].free') [enabled by default]
xively.c:250:5: warning: initialization from incompatible pointer type [enabled by default]
xively.c:250:5: warning: (near initialization for 'FACTORY_ENTRIES[1].free') [enabled by default]
xively.c:252:5: warning: initialization from incompatible pointer type [enabled by default]
xively.c:252:5: warning: (near initialization for 'FACTORY_ENTRIES[2].free') [enabled by default]
```