Network: Switch to ConnMan

Use ConnMan as networking backend instead of NetworkManager.
ConnMan: Add icon support
ConnMan: Add Manager interface

Add ConnMan Manager interface. Link the offlinemode property to
the in-flight switch and the state property to the status (icon + label).
ConnMan: Set Technology labels

Do not hardcode the labels in the UI. This would not help in translating
the labels. instead set them in the panel.
ConnMan: Add technology

Add all 4 technologies, and connect the switches to the powered
property.
ConnMan: Add services

Services list is obtained from manager interface. Services changes
are monitored via manager signal.
ConnMan: Modify Status label
ConnMan: Use Connecting state

When a service goes into association/configuration state, change the
global state to connecting. If the connection is successful the global
state will over-ride the connectng state. If the connection fails, then
set the global state to manager state.
ConnMan : Bug Fixes

Check for technology proxy before any dbus call on the proxy.
Free service name.
ConnMan: Fix global state handling

After a service is connected/disconnected set the global state to the
larger state of service and manager.
ConnMan: Fix service call callbacks
ConnMan: Add in-flight mode icon
ConnMan: Use all states to determine global status.
ConnMan: Set UI to scan

If number of services are 0 or a service trying to connect fails,
then scan for wifi technology.
ConnMan: Fix status icon

When a service trying to connect goes into "failure" or "idle" then
set the manager state to global status.
ConnMan: Bux fixes

If service goes to failure/idle after a connect, set the global status
to manager's state.
Scan at the end of ServicesChanged signal.
ConnMan: Disconnect signal only if handler id exists
ConnMan: Use g_variant_lookup instead of g_variant_lookup_value
ConnMan: Do not set tech's powered property if not needed

The switch toggled by an external event (like the extension or ConnMan
itself) triggers an unnecessary setting of the power property.
Avoid this by storing the tech's powered property.
ConnMan: Do not set manager's offlinemode property if not needed

The switch toggled by an external event (like the extension or ConnMan
itself) triggers an unnecessary setting of the offlinemode property.
Avoid this by storing it, and comparing it with the switch state.
if both are same it was an externally triggered event in which case
we dont need to call the SetProperty method. if they are different then
its the UI triggering it, and we need to call the method on manager.