Implement initial screen orientation suport

New AVD manager requires the emulator to suport portrait or
landscape as initial orientation. This implementation adds
a new field in the config.ini
hw.initialOrientation=portrait|landscape
default is portrait

Change-Id: Ifb4c7c72da3b0ca1ce5e681ca7088fbbfb584644
Add new -list-avds option.

This patch adds a new option to list available AVDs from the
command-line, this will simply print one installed AVD name
per line. This is useful to see which AVDs are installed on the
current machine without starting the AVD Manager, or looking
under ~/.android/avd/ manually.

NOTE: Output format not fixed, we may want to add more information
      like the kind of API and CPU ABI supported by each AVD.

Change-Id: Ibdcb2f99b82361f37cd8e4e4edd1bc640930fd55
Merge "Add new -list-avds option."
Merge "Implement initial screen orientation suport"