Use term_binary_heap_size(size) macro in order to calculate required heap size
for binary.

Signed-off-by: Davide Bettio <[email protected]>

…esult

New fetch function returns either `{ok, result}` or `error`, instead of
`binary()` or `undefined`.

Signed-off-by: Davide Bettio <[email protected]>

Right now there are `fetch` and `get` function, `put` name matches better
current naming.

Signed-off-by: Davide Bettio <[email protected]>

Let's explicitly mention the namespace, rather having a default one, so
applications are encouraged using their own namespace, rather a kitchen
sink one.

Signed-off-by: Davide Bettio <[email protected]>

Signed-off-by: Davide Bettio <[email protected]>