run_test.sh -V --unit doesn't run using virtualenv

Before this change, when you called the script using the -V option, the tests
were run outside the virtualenv that the script creates.
To fix it, I modified the lines of the script that run the tests to run
inside the virtualenv using the $wrapper variable.

Change-Id: I5c202727e0b5214670d54e14c80a68cc8ebec400
Closes-Bug: #1251730
Merge "run_test.sh -V --unit doesn't run using virtualenv"