[NetworkBearer] Use anonymous namespace instead of static functions

Get rid of some C-isms and follow the coding style.
[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.
Merge pull request #209 from tmpsantos/add_route

[NetworkBearer] Implement the Request and Release route backend