[NetworkBearer] Implement the "request route" functionality

This is wrong, but it is exactly what the Tizen runtime is doing, so
it was kept for compatibility.

- Routes should not be programmatically defined by the app, it has
  a strong chance of messing with the environment as a whole.
- Allowing apps to do this is probably not safe.
- We add a route just for a single IP, but a hostname might resolve
  to several IPs.
[NetworkBearer] Implement the "release route" functionality

Tizen runtime implements the "release route" by simply
disconnecting the network interface. We are doing the same here for
compatibility, but it is obviously wrong.