Simplified attachments management
Fix for android.database.CursorWindowAllocationException: Cursor window
allocation of 2048 kb failed. # Open Cursors=506 (# cursors opened by
this proc=506)
Other db optimizations
Checked weak reference to fix NullPointerException caused by:
java.lang.NullPointerException at
it.feio.android.omninotes.async.UpdaterTask.getAppData(UpdaterTask.java:154)