Utils for snake/camel case change

Utility methods to modify the input field case from snake to
camel (and vice versa) added and applied to the host API.

Change-Id: I6a6dff5c434494efa548d3f2dd0e32e3ff73dbb7
Signed-off-by: Ryu Ishimoto <ryu@midokura.com>
Merge "Utils for snake/camel case change"