Tests: Fix missing <br/> in generated html report.

Tests: add HTML report generation and a workaround to bad exception handling in sikuli.

In case of exception in python code, and since a thread is running
to observe stdout, sikuli was never terminated after an exception.
Unfortunately sys.exepthook doesn't work in that version of jython/sikuli.
Test are now written inside functions witch are passed to run_test to deal
with exception.