Android: Support AVDs with non-numeric API levels

In the case of some emulators that preview newer Android versions, such as the current Android M emulator, the API level may be something non-numeric (in this case it's "M"). This becomes "API level 0" in Qt Creator, and thus the AVD is interpreted as not supporting Qt.

It would be nice if we could either assume that unknown, non-numeric API levels were higher than the current maximum known version, or include an override option to force Qt Creator to run on a disqualified device.