Initial Android layout

This probably isn't ready for merging, but I wanted some feedback.

This pull request creates an Android project, several activities, and buttons to move between them.
I can't remember all of the screens we said we'd need, and I'm not sure the splash screen with 'Start' is needed at all.

Currently the activities are structured:

    Splash               |
      |                  |
     Menu ___           \|/
      |       \
    System <- Load
      |
    Observe

Some of these names could be changed, and I can create any other activities we may need (`Options` etc).

I still need to add some `onStart()` and `onResume()` (or something) methods to some of the activities.

I've moved Emma's c++ files into a `cpp` directory under `src`, and the NDK people can move it somewhere else later.

To build it, either use Eclipse, or start the emulator and issue:

    $ant debug
    $adb install -r bin/ourProject-debug.apk