Update test scripts

## Description
Currently, the test runner cannot run any test case, it reports that there is no test (which is false).
After including the test files in the __init__ file of the test module, some tests are failing due to changes in the implementation of some features, such as the returned value when a document was not found.

## Screenshots
Nosetests report that no test was found

Some test failing

## Files
The concerned files reside in the `healthtools/tests` folder

## To Reproduce
Run the tests, some would fail