Added AddVsie, GetVsie, RemoveVsie and GetConnectingPeer methods

Added AddVsie, GetVsie, RemoveVsie and GetConnectingPeer methods

Description: This patch adds implementation of below methods:-
1. AddVsie: This method adds specific vsie for specific p2p frame.
	interface name -> net.wifidirect.config

2. GetVsie: This method gets vsie for specific p2p frame.
	interface name -> net.wifidirect.config

3. RemoveVsie: This method removes specific vsie from specific p2p frame.
	interface name -> net.wifidirect.config

4. GetConnectingPeer: This method fetches connecting peer's information.
	interface name -> net.wifidirect

5. Added handling for "Frequency" parameter in StartDiscovery method call.

Change-Id: I5b2a643a854c20e7e6381ea7fc5d40c4c8f9733d
Signed-off-by: Nishant Chaprana <n.chaprana@samsung.com>