Updates Android SDK to version 4.0.1;

Version 4.0.1 fixes Android VideoDrawable issues/crashes;

Signed-off-by: Andreas Schacherbauer <andreas.schacherbauer@wikitude.com>
Updates Android Plugin installation text;

Signed-off-by: Andreas Schacherbauer <andreas.schacherbauer@wikitude.com>
Merge pull request #49 from AndreasSchacherbauerWikitude/master

Updates Android SDK to version 4.0.1;