Fix various warnings and clean code

According to lint + Android Studio recommendations

Squashed commit of the following:

commit 66bd28e7cd1ab51aa7a30b5188ac396f823bfdab
Author: Alan Woolley <alan@armedpineapple.co.uk>
Date:   Sat Jan 11 20:07:19 2014 +0000

    Make more fields final

commit 27dcfe945d11d8e2d56996d916aab69eb31a0d0b
Author: Alan Woolley <alan@armedpineapple.co.uk>
Date:   Sat Jan 11 20:02:31 2014 +0000

    Change access levels of fields and methods.

    As per suggestions

commit 40741358a0b12d0f2b4120ef4e29d10c7ad28c47
Author: Alan Woolley <alan@armedpineapple.co.uk>
Date:   Sat Jan 11 19:51:10 2014 +0000

    Replace string concat with stringbuilder append

    For better performance

commit 1f6554537e69123ef4d7c82f99a9067c359331a2
Author: Alan Woolley <alan@armedpineapple.co.uk>
Date:   Sat Jan 11 19:49:16 2014 +0000

    Various Lint fixes

commit 2f691afe11e8f1d3ad8b676233d3204adb2380e2
Author: Alan Woolley <alan@armedpineapple.co.uk>
Date:   Sat Jan 11 15:08:13 2014 +0000

    Suppress lint error

    Checking for vibrator requires API11, but the min level is 8.
    We already check for this though, so ignore.
Merge remote-tracking branch 'origin/beta'