Three new unit tests and safe update queries

This pull request contains some bigger changes on the API. Please review with care.

* Three unit tests for case-insensitivity, filter on two fields and input escaping.
* Changed sqlite.executeUpdate method to work with prepared statements
* Updated AddNewPatient to work with prepared statements
* Updated UpdateSpecificPatient to work with prepared statements

Test result: All tests were successful except case-insensitivity, which has never been successful so far.