support included for context string

[ramseth001]

Can define string values for title, subtitle and button texts without using getString method.

[ramseth001]

@MagicDog707 The above commit enables the user to create null negative listener.

So, instead of defining like this

.setNegativeListener(getString(R.string.dismiss), new iOSDialogClickListener() {
	    @Override
	    public void onClick(iOSDialog dialog) {
		dialog.dismiss();
	    }
	})

we can define like this
.setNegativeListener(getString(R.string.dismiss), null)