vold: Allow specifying the filesystem type when formatting

 * Optional parameter added to "volume format" to specify the filesystem
   type to use. If not specified, default is to auto-detect.
 * Add support for formatting NTFS.
 * Use mke2fs to format when not creating containers.

Change-Id: I2bc0f92d59adb9604b35a1f70febccfba68715d3
vold: Clean up warnings

 * Clean up all the dead code and get rid of all warnings

Change-Id: I8101b6314012a39e8e3a9b9b9aa8f4841b4c430d