Added 'sqlite3' to the includes when building for OS X

Sqlite3 must be included when building the package for OS X or else the app bundle will not launch successfully. This is because OS X (even the latest 10.8.4) does not have a new enough version of sqlite for Bitmessage. When including sqlite3, the OS X package builds and launches successfully.

Py2App, OSX 10.8.4, Bitmessage latest