Add support for custom kernel headers

Change-Id: I39fe4de8919e59dd75e8cb535fa0648948035c26
Fix adb sideload page on 1440x2560 layout

Change-Id: If79086b0128e57087fd87f07d56984eb2a15d8b2
Update SuperSU to 2.40

The SuperSU install process is getting rather complicated, so we
will modify the install script slightly and use it to install
all the things and stop trying to check to see if root permissions
have been lost like we used to do.

Change-Id: Ibdb64c909d2bd16e12bb35b4f31f572cc29add47
Toggle MTP during ADB sideload

Windows does not do very well if you try to sideload while MTP is
enabled due to drivers. This will toggle MTP off and back on if
MTP is currently enabled before and after a sideload operation.

Change-Id: I022dbedecc97565b50b6ae1fda8922b822f63440