Add DeleteExample and Fixed Android impl

app/controllers/index.js
Added deleteBook method for demonstrating delete functionality
Added fetch from the datasource to load existing elements when the list page loads

app/views/addbook.xml
Colored the text black to make it more readable in the android emulator

app/views/index.xml
app/vies/ios/index.xml
Added longpress functions to allow for longpress deletion from the list