Wifi: Enable IBSS options only if IBSS is supported

Show IBSS network options only if IBSS mode is supported by the Wifi driver.

This makes use of the new API isIbssSupported() of WifiManager. We have to be
careful to make the query only after we reached WIFI_STATE_ENABLED.

WifiSettingsForSetupWizardXL is left out because it does not handle these
states.

Change-Id: I072c5cc6ed36305806b469cf05c4786d22bfd418
Wifi: Add frequency selection for new IBSS

Allow users to select a frequency for newly created Ad-Hoc (IBSS) networks, and
show the frequency for existing IBSS.

Change-Id: Icaa09c9386967fdf0a88865ff2e64cc9b219da1f

Conflicts:
	src/com/android/settings/wifi/WifiSettings.java
Settings: add Advanced menu for device-specific settings app

Change-Id: Ib022a224fe71522eb2432a112d2bdf64bc08c926

Conflicts:
	res/values/strings.xml