Add some test cases for class Texts and fix some bugs

1. Handle top level request errors for batch requests
2. For Texts::addTitle and Texts::updateText log modification before
3. handling the request to filter invalid users
4. Fix error handling in Texts::updateText - checking empty texts
5. Add a header 'Connection: close' in wrapper.php
Fix a bug: invalid results from facebook not reported correctly
Add Texts::stripTitle()

Which strips titles with invalid contents from users having that title
Take escaped utf8 into consideration in Texts::stripTitle()
Fix 2 bugs

1. Graph API server can't handle curl's 'Expect: 100-continue' correctly
2. Incorrect exception propagation path of the exception 'Invalid result
from facebook'

Also, move $_POST['debug'] to global regions