avocado.job: fixing exception call on Ctrl+c

s/TestTimeoutError/TestInterruptedError/
avocado.job: don't run additional tests if user hits Ctrl+C

Ctrl+C was aborting the current test, but avocado would keep
looping through the list provided in the command line.
Merge pull request #178 from adereis/ctrl_c_fixes

ctrl+c fixes